[Psientist]

Lietenant: "Commander Supermage Sir! The battle is almost over, and we are losing badly!"
Commander Supermage: "Quit bothering me! Can't you see I'm in the middle of my tea?"

What are the parameters that regulate how long it takes to cast battlefield spells? Is it tied to fatigue, or spell research level? I've lost a numerous battles waiting for my key mages to feel like casting specific battlefield-affecting spells.

Since most of them (e.g., Grip of Winter) take quite a bit of time to have a significant effect, having commanders delay multiple turns (assuming they bother to cast them at all) seriously robs such spells of their combat value.