Understanding how spells work and planning your levelups are crucial. Like loblaw, I avoid the area effect spells in favor of some of the more devastation combinations, like nightmare and shatter. If you're working two mages with petrify and stone fist, then you've got an insta-kill on two low level enemies at the ready. I'm in the deep roads right now on my 2nd playthrough, and I'm finding the ranger ummons and the animate dead spell really useful. The skeleton can take twice the beating that my Wynne can. I'm looking forward to opening up the spell boost ability so I can crank out an upgraded summon.