[Taqwus]

Non-combat magic can be a very, very large factor except perhaps in the fastest, smallest furballs. Non-combat magic can be used to move armies, kill commanders, forge items to help commanders in various ways, summon assorted troops and commanders, gather intelligence on enemy provinces, find more magical sites, grant great health to your units, etc. You can't control spells in combat once the scripts run out (other than stipulating that the commander should cast spells or should instead melee or whatever) but for the duration of the script and outside of combat you have good control.