Use of mages

[thejeff]

I'll admit I tend to rarely use gems for regular attack spells. Battlefield buffs and the like, sure, but not the regular AoE spells.
The only one mentioned so far is ShadowBlast, which is nice, but may not be worth the micromanagement most of the time.
It can be devastating at the right time: Someone's storming your castle, hand out nice shiny death gems to all you high death mages and watch the enemy go away.