The Chaos Theory achievement:
Defeat Anomalus in The Nexus on Heroic Difficulty without destroying any Chaotic Rifts.
The Chaotic Rifts summon adds which you will be evade bugging in this exploit.
Whenever the rifts appear, simply have everyone but the tank who is tanking Anomalus jump into this place:
The healer who will be healing the tank should have instant cast heals so he can still heal the tank while jumping up and down because of LoS issues. Also, he will be getting the aggro on the ads because of his healing.
When the rift dissapears, you can jump out again and all the mobs who were evade bugged because they couldn't reach the healer will simply despawn.