"Sniping" is shooting at someone doesn't know you're there -- and thus, someone who cannot shoot back. In Castle Clash, most hero-on-hero attacks happen in the range of the target hero, so that the defending hero can either hit back simultaneously or at least move to close the range so as to hit. (Rarely you'll get a situation where a hero is near the edge of his range and is targeted; in this case, he'll retreat to his hero base drawing the enemy within targeting range.) Put generally: a hero's target can always hit back. However, that is not true of procs -- many heroes have the ability to do proc damage at range, and defensive enemy heroes in many of CC's subgames will never attack unless their hero base is within a certain range of an attacking hero. So it is possible to snipe them. That's the general idea for sniping: you find something safe to beat on -- typically, not a hero -- which will generate lots of procs, and you use those procs to remotely kill the enemy heroes.
Why Snipe?
Why Snipe?
Why is sniping useful? It's useful because it allows you to take on heroes (and thus, bases) which you could never beat in any other way.
For example, consider the 2nd most overpowered hero in the game: Skull Knight (SK). SK has among the highest hitpoints per level in the game, and his proc -- which lasts 10 seconds out of 12 -- caps the damage you can do to him. Also his proc boosts his damage to stratospheric levels. Any competent player will have lifedrain 4+ on his SK, so that even purely alone, he is nearly impossible to kill in a toe to toe fight with any normal hero or group of heroes. He attacks faster, hits ridiculously hard, and heals himself fully in every hit. If you get anywhere near him, he'll attack and proc, and then it's game over for you.
For example, consider the 2nd most overpowered hero in the game: Skull Knight (SK). SK has among the highest hitpoints per level in the game, and his proc -- which lasts 10 seconds out of 12 -- caps the damage you can do to him. Also his proc boosts his damage to stratospheric levels. Any competent player will have lifedrain 4+ on his SK, so that even purely alone, he is nearly impossible to kill in a toe to toe fight with any normal hero or group of heroes. He attacks faster, hits ridiculously hard, and heals himself fully in every hit. If you get anywhere near him, he'll attack and proc, and then it's game over for you.
Beating a high level SK toe to toe is very hard. It's also not super easy by sniping, because of SK's monstrous hitpoints. (I didn't yet mention his inherent Revive 8.) But it's often at least possible, and when possible, it's very low risk. When you're sniping, all you need is enough buildings, walls, and/or troops that are out of his range. So long as you can grind through hitpoints out of his range, you can keep damaging him without his retaliation. He never procs to cap the damage. He never hits you to stop the damage. And he never hits to heal himself. Eventually, when you've ground enough hitpoints, he dies without ever attacking even once.
So, one answer to "why snipe" is: to beat those pesky Skull Knights.
More generally, sniping is a method to beat heroes that you cannot beat safely, or beat at all, in other ways. Beyond that, another answer to "why snipe" is to keep the risk of attack low. If you are attacking a base which you don't know you can beat, sniping usually allows you to abort the attack without losing heroes if it doesn't work as you thought. This allows you to raid without waiting for heroes to revive, or to do expeditions and guild wars battles more safely. (I review the particular twists of each subgame below.)
More generally, sniping is a method to beat heroes that you cannot beat safely, or beat at all, in other ways. Beyond that, another answer to "why snipe" is to keep the risk of attack low. If you are attacking a base which you don't know you can beat, sniping usually allows you to abort the attack without losing heroes if it doesn't work as you thought. This allows you to raid without waiting for heroes to revive, or to do expeditions and guild wars battles more safely. (I review the particular twists of each subgame below.)
Which Heroes Can Snipe?
Many heroes have procs that do no damage at all, or whose procs are not long range; obviously they cannot snipe.
Of those heroes who proc with a ranged attack, most will target any non-wall enemy thing: heroes, troops, and buildings. These heroes also are not good for sniping, because there are a lot of buildings, and few heroes. These heroes will mostly hit buildings with their procs, which is doubly bad. It's bad because they are "wasting" procs on a non-threat; and it's bad because buildings are the source of the hitpoints you're using to snipe with. If you eliminate the available hitpoints that are out of range of enemy heroes, you will move in and come into contact with the enemy heroes before the enemy heroes are dead.
Of those heroes who proc with a ranged attack, most will target any non-wall enemy thing: heroes, troops, and buildings. These heroes also are not good for sniping, because there are a lot of buildings, and few heroes. These heroes will mostly hit buildings with their procs, which is doubly bad. It's bad because they are "wasting" procs on a non-threat; and it's bad because buildings are the source of the hitpoints you're using to snipe with. If you eliminate the available hitpoints that are out of range of enemy heroes, you will move in and come into contact with the enemy heroes before the enemy heroes are dead.
Note that a similar logic applies for heroes that target troops. However, at least at present (September 2016) defending bases rarely have troops, and when they do, you can usually use a different sniper.
So, in general to be a decent sniper a hero must have a long range proc that does not target buildings. We'll look at the specific heroes who can snipe below.
It is occasionally possible to snipe with a general remote damage hero like Santa, but typically only if you can find a situation where you can path him to beat through a thick wall for a while. This is rare. Also, it is not good in game modes where you are trying for 100% wins, because the damage is quite random.
One interesting thing that thinking about snipe efficiency implies is that your hero's attack number and attack speed are relatively unimportant. To see this, consider a hypothetical sniper with attack 5000, hitting a building with 70000 HP. Every seven hits, he procs. So, after 14 hits, the building is down and he has procced twice. Each proc has 5000 HP as the base for computing proc damage. Assume that the proc gets 200% attack against one enemy hero (no actual hero does this). Then he will do 20000 damage remotely. 70000 building HP have been consumed, yielding 20000 HP of sniping.
Note that the attacker's attack speed has no effect on this conversion at all, other than how long it takes. If his attack speed is 1000ms, it takes 14 seconds. If his attack speed is 1500ms, it is 21 seconds.
Game Modes Discussed
Sniping Theory
When sniping, your goal is to turn hitpoints of things that you can safely attack into procs that kill heroes you cannot safely attack. When thinking about it, I like to keep in mind a concept I call "sniping efficiency" (also "sniper" or just "snipe" efficiency), which is the ratio between a sniper's attack damage, and the proc damage he produces. Since every hero's proc damage is based on his attack damage, the ratio is largely determined by the hero's particular skill, and the skill level.
One interesting thing that thinking about snipe efficiency implies is that your hero's attack number and attack speed are relatively unimportant. To see this, consider a hypothetical sniper with attack 5000, hitting a building with 70000 HP. Every seven hits, he procs. So, after 14 hits, the building is down and he has procced twice. Each proc has 5000 HP as the base for computing proc damage. Assume that the proc gets 200% attack against one enemy hero (no actual hero does this). Then he will do 20000 damage remotely. 70000 building HP have been consumed, yielding 20000 HP of sniping.
Note that the attacker's attack speed has no effect on this conversion at all, other than how long it takes. If his attack speed is 1000ms, it takes 14 seconds. If his attack speed is 1500ms, it is 21 seconds.
Less obvious is that the sniper's attack number also has no effect on the snipe efficiency. It affects only how long it takes. To see this, consider what happens when we evolve the hero, and get his damage up to 10000. Now he kills the building in 7 hits, and accordingly procs one time only. This proc does 20000 damage: 200% of the 10000. So, 70000 to 20000. The sniper has the exact same efficiency. What this means is: don't worry too much about evolving your snipers or getting their levels really high. I find evo1 180 is fine, and indeed I did pretty well even with level 160-180 non-evo'ed snipers. What matters most for sniping is the snipers' skill level. Get those skill levels up!
Now let me back off of that somewhat. For one thing, evolving your snipers is good because it allows them to have an artifact, which can be helpful in ways outside of damage production. Also, higher level snipers have more hitpoints, which allows them to deal better with damage from towers, autoproccing enemy heroes, and other sources.
Another reason for higher level snipers is that higher attack can actually increase sniper efficiency; this happens when an attack kills a thing and there is overkill. You get energy per blow regardless of damage done, and proc damage is not based on the damage that the triggering blow dealt, but on the sniper's attack stat. Overkill effects are most relevant when you are using a sniper and he wades into a group of troops. Most kinds of troops he will easily one-shot; his procs still do full damage. Here, you want the highest attack possible for your sniper.
(Note that overkill on proc attacks works the other way, lowering efficiency. But since overkilling heroes is not possible without killing them, and killing them is what you're trying to do, it's usually not a problem. Also, there are far fewer hero targets than buildings plus (maybe) troops and walls... so in general, high levels benefits the sniper.)
Another reason for higher level snipers is that higher attack can actually increase sniper efficiency; this happens when an attack kills a thing and there is overkill. You get energy per blow regardless of damage done, and proc damage is not based on the damage that the triggering blow dealt, but on the sniper's attack stat. Overkill effects are most relevant when you are using a sniper and he wades into a group of troops. Most kinds of troops he will easily one-shot; his procs still do full damage. Here, you want the highest attack possible for your sniper.
(Note that overkill on proc attacks works the other way, lowering efficiency. But since overkilling heroes is not possible without killing them, and killing them is what you're trying to do, it's usually not a problem. Also, there are far fewer hero targets than buildings plus (maybe) troops and walls... so in general, high levels benefits the sniper.)
Also, while attack and attack speed are not that important, you do want enough of them so that your primary sniper can go through most of a high-level base in about 2 to 2.5 minutes. Since you have three minutes per attack, this leaves 30 to 60 seconds for cleanup, which is usually plenty. (Sometimes a nest of highly garrisoned magic towers can take quite a while to break.) If you find that you're running out of time in an average sniping attack, you should work on getting your snipers' levels up.
Snipers Reviewed
Since sniping can only work when there are non-hero hitpoints of some sort to chew on, there are only a handful of heroes that have restricted enough targeting so as to be useful for sniping. These heroes are summarized in the following spreadsheet; I'll discuss each individually. (Note that Triton is not listed, but he can snipe, albeit far more weakly than any legendary hero. If you are just starting, you might find a Triton useful. But please buy TG and Griz ASAP.)
Pixie can snipe, but she's a weak sniper for the most part. She has a number of problems. Foremost is her weak sniper efficiency: she simply isn't great at converting hitpoints into proc damage. It is true, though, that her efficiency is not as bad as the spreadsheet makes it look, because it factors in her 3 target limit. Since sniping when there are 1-3 targets left is important, she's not as weak as the spreadsheet makes her look.
One other nice thing about Warlock is the effect on himself of his Fire Shield. It helps protect against damage from arrow towers, enemy procs, etc. Think of it this way: deflecting 40% of damage for 5 seconds out of 7 gives roughly the same protection as a Flame Guard 7/8. So Warlock is your best bet as a "tank sniper". This is particularly important in Guild Wars, where you will often find bases with max level, highly garrisoned arrow towers.
Since sniping can only work when there are non-hero hitpoints of some sort to chew on, there are only a handful of heroes that have restricted enough targeting so as to be useful for sniping. These heroes are summarized in the following spreadsheet; I'll discuss each individually. (Note that Triton is not listed, but he can snipe, albeit far more weakly than any legendary hero. If you are just starting, you might find a Triton useful. But please buy TG and Griz ASAP.)
#5: Pixie
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| Pixie |
Another problem is that Pixie flies. Fliers never target walls, so there are a fair number of bases that other heroes can snipe that she can't. This matters when raiding in particular, because you cannot choose which heroes to bring to a raid on a per-base basis. However, it also matters (albeit less) in any mode, simply because your resources are finite. Experience and hero shards are finite. Every experience point or skillpoint that you spend to develop Pixie can't be given to any other hero. And while you can in theory swap around crests and artifacts on the fly, doing so is a pain in the ass.
On the plus side, Pixie targets only heroes, which is the best target setting for a sniper. Also, she is at least partially self-healing, which is a useful thing. Her skill is also useful when sniping with multiple snipers against an enemy Dread Drake. DDs tend be hard to kill with mass snipers because they autoproc and their proc protects them. Pixie will strip that away.
#4 Thunder God
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| Thunder God |
Thunder God is an often overlooked sniper. I know I stopped using mine for a long time; indeed it is only writing this article that I seriously started using him. The problem is, of course, that his proc is at least somewhat unpredictable; it can hit anything. But it's not nearly as random as you might think, and its randomness does not always matter. I love my TG now.
TG's sniper efficiency can be huge due to the large amount of damage his procs do and their area effect. But even when 6 heroes are present it won't necessarily hit all of them, or even any of them! TG loves to proc on the enemy townhall, and if within range (seems to be about 1/3 of the playfield edge) will usually choose to hit it. So he's often unusable in the sense that he expends way too many of the hitpoints he is consuming to nuke the townhall.
TG's sniper efficiency can be huge due to the large amount of damage his procs do and their area effect. But even when 6 heroes are present it won't necessarily hit all of them, or even any of them! TG loves to proc on the enemy townhall, and if within range (seems to be about 1/3 of the playfield edge) will usually choose to hit it. So he's often unusable in the sense that he expends way too many of the hitpoints he is consuming to nuke the townhall.
However, if you can arrange to drop him and keep him far from the townhall, or else to take down the townhall first (with some other sniper, or sometimes TG himself), then he can be excellent. In my experience, if the townhall is not available he'll often target troops. But after that, he prefers heroes. He does this often enough to use in any game mode. In a raid, if he doesn't do what you expect, you can always take the loss. In Expeditions and in Guild Wars, you can keep restarting until he does open up on enemy heroes. Once he starts hitting them, he tends to keep doing so. From observation, I think that once TG selects a target for his proc, he'll keep hitting it until it dies. Only then does he retarget the proc.
Unlike any other sniper, TG is a melee-ranged attacker. This is both a strength and a weakness. It is bad in the sense that in general TG cannot snipe for as long as other snipers can before being engaged by the enemy, because he has to go closer to any given building. However, it can be a real strength in giving TG a path that a longer-range hero won't take. Often people put buildings along a both sides of wall around their base. Because TG must be right next to a building to hit it, when he kills it often the next building on the outside will be his next target. By comparison, a ranged hero hitting the same building is much further from it, and to the ranged hero a building on the other side of the wall is closer. The ranged hero will fly over the wall, or run around it, and end up engaging enemy heroes sooner.
One other important way that TG is great, is that he can be obtained for shards. You don't have to wait months to roll him. Every single sniper team, IMO, should have a TG (and a Griz; read on).
Finally, TG's proc has the side effect of stunning. This is, of course, almost useless unless confronting enemy heroes. But if you have to fight, it can occasionally be very helpful.
#3 Grizzly Reaper
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| Grizzly Reaper |
Grizzly Reaper (aka Griz) has his weaknesses as a sniper. One is that he flies. Just as with Pixie, flying is mostly a weakness because it precludes the ability to pound walls. This doesn't always matter, but when it does, you'll wish for a different hero.
Also, Griz's proc targets both troops and heroes. Troops in defending bases are relatively rare in CC, at least at present (September 2016). But when they are there, they can be a huge boon for a sniper -- but only if using a hero whose proc targets only heroes. Troops protect against Griz: he'll spend most of his procs snuffing them until they are all gone. Only then will he focus on the heroes.
Apart from his weaknesses, though, Griz is among the better snipers. He does very good damage, and with high skill can affect every defending hero at once (which makes him more predictable). Also, like TG he is available to buy with shards. He should be the second hero you buy with shards, after TG. Finally, Griz's proc has the useful side-effect of self-healing, albeit a modest amount. You'll still want Lifedrain on him, but his self-healing means he can get away with a bit less of it than other snipers.
#2: Aries
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| Aries |
Aries is dominant in many game modes due his nasty ability to silence enemy heroes via his Calamity skill. He's also a good sniper.
Aries really only has one downside as a sniper: for some reason he gains only 12 energy per attack, not 15 like other heroes. Thus it takes him 2 extra hits to proc. This reduces his sniping efficiency. However, it is quite good to begin with. It is competitive when there are 5 or 6 enemy heroes alive, but then it declines when you've killed the easier ones.
On the plus side, like Pixie, Aries only targets heroes. Unlike Pixie, Aries is ground-based so you can get him to beat on walls. Also he has fairly long range, which is generally helpful. And if you are willing to risk confronting enemy heroes, Calamity is about the best skill there is.
Aries has several other less obvious advantages.
First, because Aries is so dominant in so many subgames, you should level him rapidly, evo him ASAP, and get his skill to 9+. As such, you might as well put him in the sniper team. Even if you don't give him lifedrain, he can snipe in certain circumstances and help clean up.
Second, Aries can be useful as a solo sniper against bases which have really strong autoproccing defenders. Aries removes energy with each proc; no enemy hero can ever autoproc against only Aries. If you put in Aries with another hero, it's kind of unpredictable what happens. Depending on how they synchronize, Aries may shut down enemy autoprocs, or he may not.
But the most powerful thing about Aries is that Silence disables not only skills but also many talents. This includes Revive. That is, if you kill a hero with Revive while he is Silent, he doesn't revive. This is generally not that important, because most Revive talents are coming from crests and only revive with 15% or 20% hitpoints. Usually if you can snipe a hero at all, getting another 20% is also doable. However, Skull Knight has Revive 8 -- he revives with 100% hitpoints. Without being Silenced, he's almost always the last enemy hero to go down, and often his sheer hitpoints (along with his unbeatable toe-to-toe abilities) are the reason why a sniping attack fails or has to be aborted without three stars. So, it's a big deal to have a way to kill SK on the cheap.
Note that Calamity does not impose Silence (and thus disable Revive) until after the damage associated with that Calamity. In other words, by himself and using only procs, Aries cannot kill heroes without them reviving. He can only do it if accompanying some other sniper, or in toe-to-toe combat. The way I use him is to put in my primary sniper (Warlock) first. Then I watch the enemy SK and put in Aries when the SK is nearing dead. It doesn't always work, but when it does, it's awesome. You can often try to kill SK this way repeatedly in Guild Wars or an Expedition, quitting and restarting until you succeed.
#1 Warlock
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| Warlock |
I am embarrassed to recall it, but when I first rolled my Warlock I left him as a level 1 nobody for several months. I just didn't understand his utility. I was sniping already then, using Griz mostly. But once I started really thinking about sniping, and about how I always seemed to end up with a few of the same heroes living longer than all others, I looked at this guy's stats again... and wow! Best sniper.
If you look at the spreadsheet, Warlock doesn't really jump out until you imagine the effect he has after the enemy is down to three heroes or less. And here, Warlock shines. Only TG can approach his sniping efficiency, and that's only if TG is hitting all remaining heroes. Whereas Warlock never targets anything but heroes. Unlike TG, Warlock's normal attack is ranged, which is usually superior for most sniping.
Unlike Griz, Warlock moves on the ground. So you can sometimes find bases where you can get him to beat on a wall. And also unlike Griz, he targets only heroes. This means you can use enemy troops as snipe-fodder.
Other Considerations for Snipers
Talents and Crests
It is highly helpful for a sniper to have lifedrain. In fact, I'd say it's mandatory. Although it is possible to snipe a few relatively common base designs without healing, most enemy bases have bombs and towers that you need to tank; also there are some defending heroes that can proc defensively. Even level 2 lifedrain makes a big difference, but I would want at least lifedrain 4 on my primary sniper, and even then there are bases that put out unsustainable damage. I have level 6 lifedrain on my Warlock (evo 1 189), and he still occasionally runs into bases sporting massed high-level and highly garrisoned arrow towers that are simply too hot for him to handle. It's rare, but it happens, particularly in Guild Wars.
Excepting lifedrain, other talents are not that important. You definitely do not want Slow Down, Heavy Blow, or Deadly Strike. These crests get extra damage against their possessor's main target, but no extra procs or extra proc damage; that means they decrease your sniper efficiency.
It is highly helpful for a sniper to have lifedrain. In fact, I'd say it's mandatory. Although it is possible to snipe a few relatively common base designs without healing, most enemy bases have bombs and towers that you need to tank; also there are some defending heroes that can proc defensively. Even level 2 lifedrain makes a big difference, but I would want at least lifedrain 4 on my primary sniper, and even then there are bases that put out unsustainable damage. I have level 6 lifedrain on my Warlock (evo 1 189), and he still occasionally runs into bases sporting massed high-level and highly garrisoned arrow towers that are simply too hot for him to handle. It's rare, but it happens, particularly in Guild Wars.
Excepting lifedrain, other talents are not that important. You definitely do not want Slow Down, Heavy Blow, or Deadly Strike. These crests get extra damage against their possessor's main target, but no extra procs or extra proc damage; that means they decrease your sniper efficiency.
Generally, I would recommend using your other talent/crest to optimize the hero's utility in game mode(s) other than the sniping modes.
Most talents that are pretty nice in other game modes are not that important for a sniper, because you generally have time and are not expecting to die ever. Thus, for example, Revitalize is the equivalent of a building or two. Or consider Revive: if you died once, you're almost certainly going to die twice. Still, Revive can be nice in giving you time to notice and quit the attack.
A lot of talents have effect only on the immediate target or vicinity, but do not have any effect on sniper efficiency. These include Scatter, Condemnation, Corrode, etc. You might want these if you are going to risk letting your sniper confront enemy heroes one on one. Otherwise, something else might be better. There is no harm in them, at least.
In general, the offensive crests (War God, Bulwark) may be helpful on increasing the effective attack speed of lower level snipers. But since they have the same effect as raising hero level, you won't need them forever. Apply them with crests, then level up and use something else once you are wiping bases out fast enough. Or just leave them; they don't hurt. They do marginally increase sniping efficiency via overkill.
Berserk can speed up some of the slower snipers nicely. Do stay aware of a sniper's cooldown, if he has it, and don't speed your sniper so fast that he wastes attacks with a full energy bar.
The defensive crests (Flame Guard, Scorch, Stone Skin, etc.) are similar to the offensive in the sense that getting up hero level does roughly the same thing. I rate them less important since a lot of the time your snipers won't be taking any fire at all. However, they are more useful at times since there is always a tougher base out there that needs more defense.
Artifacts
No artifact has any direct effect on sniper efficiency. So it doesn't matter much which you use, other than that the Goblet of Life is a poor-man's lifedrain, and can be helpful in keeping a sniper alive. Other artifacts can boost defense (Victor's Emblem, Lightning Rock) or offense (Axe of Strife, Blitz Scroll). The Blitz Scroll acts like a Berserk crest: speeds up attack but can reduce sniper efficiency if the hero has a cooldown.
I use the Axe of Strife on my snipers, since it does marginally increase sniper efficiency via overkill.
Bases to Avoid and Bases to Hit
Many bases in CC are unique, and must be judged individually. However, there are a number of common base patterns, which are helpful to learn for the purpose of sniping. Some common bases are usually snipeable; others are usually not.
HBM Bases - Snipeable
The general idea in most HBM bases is to put most buildings outside of the walls, using walls to funnel monsters in to where the heroes can hit them while they stupidly/helplessly walk by.
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| HBM base |
These bases may be be great for stopping waves of heroes and monsters, but they are bad against snipers. A sniper (sometimes two are needed, as in the case above) can hit the buildings outside of the main base.
Anti Guild Wars Bases -- not snipeable
Since the advent of the Guild Wars subgame, people have started hardening bases a lot. Anti-sniping is a key element of this. Most of the common designs you'll find in Guild Wars cannot be easily sniped. Increasingly, Guild Wars anti-snipe bases are appearing in other modes too, as people use the same base for all modes.
Here are some examples of "Guild Wars" bases; all of these examples are not easily sniped, if snipeable at all. If they have low-level heroes (level 180 or lower, not evolved), maybe. If they have lots of troops, maybe.
You should become familiar with these kinds of bases to the point where you can detect one that is weak. A weak base will have some flaw in it that allows you to snipe. Most common are "V" bases where they did not make the walls thick enough at the point; this permits you to beat on a thick wall using one, or sometime two, snipers. Sometimes you'll see "brackets" bases with too thin walls; here you may get a sniper on either wall beating on it. "X" bases don't tend to have any obvious and common failure modes beyond low-level heroes and troops.
The "X" base (four short wall sections with four gaps):
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| "X" base |
The "brackets" base (two long walls with two gaps):
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| "Brackets" base |
The "V" base (one large walled side):
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| "V" base |
Four Corners Base -- often Snipeable
Before Guild Wars, probably the most common base you'd see was the "Four Corners" base.
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| "Four Corners" base |
"Four Corners" is still fairly common. It has centralized heroes and a surrounding wall with openings on two sides, but the key feature is four clumps of buildings in the corners. This is a moderately effective anti-sniping defense; a single sniper obviously cannot do it alone. But four snipers -- or three, and a Cupid or Druid to amp them -- often can. This depends on the defending hero levels: if they are non-evo 180 or lower, it will probably work. Above that, maybe or maybe not. If they have troops and you have at least two of Pixie/Aries/Warlock, it will probably work.
Also, look for insufficiently thick walls on the two closed sides, where you may be able to get a hero to beat the wall. (The base pictured above is certainly weak on the north side and probably on the south also.) That hero may be a sniper (TG is often good), or -- after a delay to let the snipers work on the corner buildings -- a cleanup hero like PD or Santa.
Raiding has one downside the other two modes don't have: you cannot see a base before choosing the heroes you are going to attack with. This is not a serious handicap, but it is a handicap of sorts.
There are several ways in which raiding is a lot easier than the other two modes.
First... did I mention that you can quit out at any time during a raid, and lose only a handful of honor badges? No, I don't think I did say that. Well: you can quit out at any time during any raid, and lose only a handful of honor badges! Yes. It's true. Use it. It's slightly better to get at least one star, and that's often doable. Then you gain an honor badge or two! But you can quit with no stars and nothing really bad happens.
Second, when you raid you can use spells. This is nice; spells allow you to deal with an enemy in toe-to-toe combat. Snipe away, then when you get close, if you've got a decent chance to prevail, help out your sniper with a healing (for lesser enemies) or invulnerability (for nastier enemies) -- or both -- and see what happens. Often the sniper will prevail.
You can also snipe for as long as possible, hoping to weaken or kill as many enemy heroes as you can, and then -- when the sniper is soon to be engaged anyway -- dump in a full-scale assault (all your heroes and spells as needed).
You can always quit if the toe-to-toe isn't going well. Well, you can usually quit in time. Even losing one hero to, for example, an unexpected Atlanticore Hero Totem is annoying, because it means you have to wait to raid, or else raid without the most desirable lineup. So pay attention.
Oh, and one other thing... you can quit out at any time during any raid, and take only a tiny little penalty of a handful of honor badges. It's really quite handy, that.
Expeditions are similar to raids, with two main exceptions. First, you can use any of your heroes, and you get to use up to 10 of them at a time. (The actual number depends on your nobility.) Second, if you quit out of an expedition attack before getting any stars, it doesn't count, and you can try again. You do lose any heroes that died for the remainder of that expedition. (This is one reason sniping is very helpful in expeditions. It's probably the mode where sniping is most important for doing well.)
One other mild difference is that Expedition bases tend to be chosen to be fairly attackable; that is, at least early in the expedition they tend to be easier than the average base you see on a raid.
In general, you can three-star many bases on an expedition that you could not in a raid, simply because you can "zero-star quit". That is, you can quite and restart as many times as needed to get a relatively rare event. For example, having your Warlock hit an enemy SK with each of his first three procs is pretty rare. (Assuming 6 enemy heroes, it's about 1 in 8.) But if you need it, and you have the time to play, you can keep trying until it happens. Similarly, if you need a sniper to path just so in order to get him to beat a wall, you can keep trying slightly different drop spots until he does.
You can also use the zero-star quit in order to scout a base for hidden or non-obvious things. Hidden things include locations of hero traps and hero totems. Non-obvious things include pathing (particularly seeing if you can path a hero through a wall), and the potency of enemy towers.
You get to pass on up to 5 bases during an expedition; don't waste these. Often I will accept an easy two-star win if a three-star win is not available, rather than use up a pass. This is particularly true early in the expedition. Note that even using non-snipers, it is often possible to get 1 or 2 stars from a "Four Corners" style base.
One trick I have for sniping on expeditions is that I have a level 1 Cupid that I occasionally use. (I call him miniCupid.) The idea is that a level 1 hero does very little damage, and therefore will practically never manage to kill even a single building; so he costs almost nothing in terms of using up building hitpoints. But Cupid's skill effect does not depend on his level. So you can get Cupid-injected energy without losing building hitpoints. I boosted miniCupid's skill to level 2, so that he gives 15 energy and +15% damage when he procs. Note that his +15% damage does not increase sniper efficiency (just speed), but his +15 energy does boost efficiency. I use miniCupid occasionally when I am facing a base where I try a few times but I find myself falling just short of a safe win using my main sniper(s). Just be careful. You can't place miniCupid in the range of any tower except cannon towers (which can't target flyers). Also, any defensive hero who can auto-proc will kill miniCupid in one shot. Before using a miniCupid, carefully scan the enemy hero lineup to make sure there are no autoproccers. (Heroes that autoproc: Warlock, Dread Drake, Harpy Queen, Phantom King.) Even when there is an enemy autoproc, sometimes you can snipe for a while with your main sniper, then when the enemy autoproccers are all dead, put in miniCupid in a corner.
There is no other hero that in miniHero form will increase sniper efficiency. There are several heroes that might have marginal benefit as miniHeroes. For example, a miniAries could be nice in dealing with enemy Skull Knights and other heroes with Revive. I have not tried that, though; perhaps if you have a lot of extra Arieses you might. One other thing you might try is a highly skilled miniCupid. Upping Cupid's skill won't help, beyond a point, for the heroes with cooldowns. However, for TG and Griz, who lack cooldowns, any amount of extra energy injection will help. There are also a number of heroes that in miniHero form might be useful to aid toe-to-toe fighting... but since this is a sniper guide, I'll leave that to you.
Guild Wars bases range from very hard down to very easy, since you can attack any base in the enemy guilds. But in general you'll want to attack the hard ones, since they give more points. As such, Guild Wars bases tend to be much harder than expeditions and harder than raids. You'll often run into maxxed out towers with full level 7 garrisons, in a base with full level 200 evo2 heroes including SK, Ghoulem, and Dread Drake. These can be challenging even when they not well designed.
As with expeditions, because a zero-star quit doesn't count, you can scout out an enemy base. In fact in a Guild War attack you can scout even further, since you can get all your heroes and troops killed without losing them (so long as you don't get 50%).
As with raids, you can afford to go "all in" in a guild war attack. You may lose the use of heroes for 15 minutes, but that's usually worth it if it gets you three stars.
As with expeditions, because a zero-star quit doesn't count, you can scout out an enemy base. In fact in a Guild War attack you can scout even further, since you can get all your heroes and troops killed without losing them (so long as you don't get 50%).
As with raids, you can afford to go "all in" in a guild war attack. You may lose the use of heroes for 15 minutes, but that's usually worth it if it gets you three stars.
