Three Minutes with the Centaur Ruler

the target

This is my new strategy for doing mass damage to Boss 5 (Centaur Ruler and Rage Goblin).  Note that this strategy works only when both bosses are alive, since it relies on using the procs generated by the easily-hit Centaur to remove the hard-to-hit Goblin from the fight.  I have a different lineup for fighting only the Goblin; you can read about it at this post.

My strategy requires a Pumpkin Duke to work.  If you have no PD, sorry, you won't be able to do mass damage to boss 5 (and probably not other bosses either).  Other than PD, however, all of the important heroes that I use can be bought for shards.

Note also that this strategy works without using Skull Knight.  (I don't have SK.)  If you have a Skull Knight, you may be able to use him as a tank so that you get all six heroes beating on the enemy for 3 minutes; and if so, that would be a superior strategy.

Overview

Here's the general idea: use healing and debuffing to deal with the Centaur Ruler, who is easy to hit.  The Rage Goblin is not easy to hit, and thus terribly difficult to debuff.  You deal with him by slowing him.

Your team is basically a scatter team, but you need to have Ice Demon in among them.  Your PD is your tank.  You need at least one good debuffer on the team to debuff the Centaur Ruler.  You'll use one hero as a sacrifice to keep the Rage Goblin away from the rest of the heroes long enough for the team to amp up, and thus for Ice Demon to slow the Rage Goblin to a crawl.  The Rage Goblin will kill the sacrifice, but by that time he is too slowed to reach a second hero.  

The Team

It doesn't matter who your sacrifice hero is.  His identity, level, and skill level are not important, since he will be in the fight only about 12 seconds or so before dying.  Be sure to give him enough scatter so that he does not cause the Rage Goblin to proc.  (It is helpful to have Phantom King as one of your other heroes, since PK's proc scatters both bosses.)

my boss 5 team

I use Cupid for my sacrifice hero, because he does help PD amp up, and my calculations suggest that after the ramp-up period I do not benefit from Cupid's damage boost.  Also my Cupid is fairly high level, so he does a bit of damage to the Rage Goblin before dying.

Your PD is there to get the team sped up.  (He also amps up damage.)  You need a quick amp up.  I am not sure how quick.  My PD has Celebrate 10, Berserk 4, Revite 3, and Blitz Scroll 5.  He also gets energy from Cupid.  This definitely gets it done.  You probably don't need this much.

Your Ice Demon needs a medium-high skill level.  I am not sure how low you can go and succeed.  Mine has skill level 7.  You probably don't need that much.  His level and other attributes don't matter.

Your debuffer needs to debuff about 70000 HP/s down to a level that your PD can tank.  Obviously Druid helps with this.  My current debuffer is Shaman, with skill level 7.  He works great; when amped to max speed he stacks ~6 times which reduces the DPS to about 5200 DPS, which my PD can tank easily with Druid's healing.  I am going to experiment with using Succubus instead.

For my two remaining heroes, I have Druid (for healing PD), and Phantom King, whose proc I need to help my Cupid scatter the Goblin.  Also, PK is among the most damaging heroes in the game at max speed.

Remaining slots (if you have any; I don't) should be filled with high DPS heroes.  Just be sure that you have enough scatter so that neither boss procs.  

Deployment

The drop sequence looks like this:

(1) Wait for Rage Goblin and Centaur to separate at least a little.

(2) Drop PD on the far side of the Centaur from the Rage Goblin.  Keep enough range so that he will move into the Centaur's range in about a second

(3) Select your sacrifice hero.  Mine is Cupid, so I am assuming that.

(4) As soon as Centaur targets PD, drop Cupid in on the far side of the Rage Goblin from the Centaur.  Drop him just at the edge of the Goblin's targeting range.

(5) Drop all remaining heroes close to Centaur; exact placement doesn't matter, but on the far side from the Rage Goblin.

(6) Quickly hit Invincible before the enemy hits either PD or Cupid.  If you are too late and either hero dies, "End Battle" and restart.

Result

If you did it right, when Invincible ends, the Rage Goblin will kill Cupid and then move to a next target, but super slowly.  So slowly, in fact, that he does not normally reach it before 3 minutes are up.  

Your five remaining heroes are amped up to max speed and beating away on the Centaur Ruler.  So you go the full 3 minutes and score massive damage.

Here's an example showing my team in action:

In the screenshot, you can see the tombstone where Rage Goblin killed Cupid earlier.  He has been moving towards the Druid for a minute and a half at this point.