Alright, basically anyone who has a taunt can do this. The third boss, Chrono-Lord Epoch, can be dragged into the fireplace to evade glitch him therefor resetting his HP. So, what me and my friend did was every time he got to 50k hp would drag him in there and start screaming at this rogue to interrupt his healing spell. After the third time we stopped and left to make the timed run, still got it by a couple minutes. Be careful of your friends aggro if ur the tank. It's easy to pull as you see in screenshots.
But basically its a funny little exploit to piss off group members.