[Arker]

Exactly. Except for their tendency to senselessly cast BoW and then kill each other with it, this is a very handy tactical tool.

Also it seems that when you put them on 'stay behind troops' they will fire ranged weapons on and off, keeping their fatigue down and their spellcasting going longer, but on 'cast spells' they ignore their ranged weapons and just cast until they pass out.