[Eru]

You're only really going to run into mana problems if you're trying to kill a monster with magic damaging spells or just cast Energy Vortexes to tank monsters that are too tough for them.

There are a lot of other things you could be using, like Archery for damage, provocation to have another monsters tank instead of an EV, walling the monster after paralyzing so that they can't move while you shoot them, etc.