Treyloth D'Kulvith
Reaching Rot (AOE disease DD) hits at range above 10m, Searing Rot (short range AOE (less than (m) disease DOT + throw)
What does this information mean?
Treyloth D'Kulvith will mem wipe at 75%, 50% and, 25% health. You need to fight between 10m and 5m of him to avoid both of his AoEs. He also places an arcane detrimental on the raid which causes your spells to reflect.