Me and my friends were doing Grim Batol Heroic mode a few days ago.
In the instance there's a mob named "Azureborne Warlord". This mob, has an ability called, "Conjure Twisted Visage"
When the mob uses this ability, it will create a "blue hole" on the ground, the position is randomly chosen, though it seems like most of the time it spawns just beneath the mob.
While standing in this hole, you get a 50% damage increase.
At the pack just before Erudax, there are 5-6 mobs, and one of them are the Azureborne Warlord
So we decided to cc that mob, kill the rest and bring the warlord to the boss. By doing so he spawned several holes. A huge damage increase.
It's extremely simple, step by step:
1. Crowd Control the specific mob. And kill the rest.
2. Bring the mob to the boss and start fighting.
3. Stand in the hole.
4. Pr0f1t!?