After reading your guide I decided giving AoE mayhem a try.

My Fire/Dark is amazing. I rolled on a 7 member team through three levels just dropping entire mobs throwing down a tar patch, then comboing into RoF, Fireball, and later Firebreath. My teammates were amazed. I'd just tell them "watch this" and I would lay waste.
Given the nature of rolling on fast pace teams the combo wasn't always up, but when it was I'd just tell my team "stand back" and take out an entire mob.
I can't wait for higher levels when I can Fearsome Stare, Tar Patch, Darkest Night, Aim, Rain of Fire, Fireball, Firebreath, and wonder at what point everything will be dead.
Edited 'cause I thought of a better combo