When you start casting, there's a green button that pops up that says "Area of Effect"... Click it..
AFAIK, You can only turn it on when you start casting which is stupid, but just the way the game is. Once it's on, it stays on..
Edited, Dec 12th 2010 9:05am by Sidicas
Actually you click the spell, then it allows you to toggle AoE and then spell goes off. TC I think Shell and Protect are cone shaped AoE, I haven't got them myself before but if they are you just toggle AoE on, ask party to "gather" in front of you and face them so they are within the cone then cast the spells.