He gets hit by skills so seldom. I tend to kill all creatures but one and then just have them all guard for a while, hoping that the last creature will cast a spell on Kris. But if ever he does he just doesn't learn anything. I've been through several dungeons now without gaining even one new spell.

Edit - ok, after probably 296 attempts he now learned Clean Sweep although having guarded. Phew, I wonder how many spells he did not learn.