Best 4 person all caster/priest group

[Keebz]

The fact is 4 casters at 60 should be killing cool targets, not root rotting trash is Seb. It's just this weird struggle to prove... something. The guy needs help.

What do you think the hardest mob 4 beefy casters could take down, and what's the comp?

Epic mobs like Ixi, General, etc all seem doable. I wonder if you could do KD or Fay.