How to target specifically with spells?

[Taqwus]

Single-unit spells tend to focus on high-hp units.

This is not necessarily a good strategy, mind you; for instance, it can be a waste of time trying to Soul Slay a high-hp high-MR Abomination. But generally it's not too bad. 'Petrify' doesn't really seem to get wasted on militia.

I've noticed a seeming emphasis on Enslave Mind on routing units, too. Interesting.

Targeting individual units with spells "cast at mages" would give certain paths extreme advantages with the defender-fires-first rule -- imagine having all your commanders smacked down with Gifts from Heaven first turn. Not fun.