[LintMan]

I think higher level mages are supposed to have a better chance of killing the target, but even so, Stream of Life seems to be a marginally dubious choice for an attack spell, given its chance of healing/berzerking the target.

Anyway, it should be fairly easy make your own mod to make Stream of Life not be cast so often. You just need to mod the spell to cost, say, 1 gem. Then your units won't cast it unless you give them gems. I think there's a mod on Sunray's web site that does something similar for Magic Duel that you can probably use as an example.