I like to troll tanks in Auchindoun by casting Rain of Fire over them on the "Destruction Warlock" mob that casts his own version of Rain of Fire. It works a little too well, so I am kind of worried about giving the spell such a non-negligible cost.
Our AoE has worked so well on Live for years now that the idea of changing that is depressing. Oh well, have to make change for change's sake just to keep the game "fresh".