Bind Thrall
Circles: Water, Mentalism
Description: Permanently take control of a unit who survives a battle under the command spell.


For balance I think upkeep should equal standard upkeep (gold, food, mana) for the unit plus mana per turn equal to the unit's willpower without buffs or debuffs (maybe higher with some level adjustment taken into account). I could see this spell being potentially very powerful in certain circumstances so balance may be a huge factor. Think it would work best as a strategic spell that gives the player the option to keep a unit who survives a battle under the command spell.


Based upon this:
http://dnd-wiki.org/wiki/Bind_Thrall_(3.5e_Spell)