Title says, well... nothing.
What I was thinking, was that bosses in raids could have "gimmick" enrages, and not simply +1000% damage, kill tank 1 and 2, kill DPS, kill healers.
For example I can imagine :
- Marrowgar splitting his axe into two 1h axes and making a huuuuuge bonestorm
- Saurfang spawning 50 beasts with +300% movement speed
- Deathwisper swirling around casting a Frostbolt every 0.1sec on a random raid member
- Lich King picking one raid member, killing him, and then casting Corpse Explosion on him
- Putricide covering the room with goo
- Sartharion flying above the raid spitting fiery balls
- Thaddius putting random + and - signs on every body, pulling them all in melee and stunning them all
See what I mean ? That could be a nice addition to the game imo.