So at the end of a chapter our reward is a level, an artifact, or a companion? I have great personal methods of securing companions so unless Zaer purposely creates an amazing companion I can't resist who is also immune to all those things, I can't see myself choosing that.
The Level up is so enticing, id get level 7 spells, my cohort would get control creature, so many other goodies too.
Still I think im going to go for artifact. Ive wanted the Despoiler of Flesh in every D&D game and have never gotten my claws on it in any of them. The Ruby Rod of Asmodeus is pretty tempting too but I can't think of many reasons he would just let me have it.
And yes, Kunoichi. The whip is for Balor, he would get the Balors entangle ability and potentially it's body of flames too making whip attacks drag foes kicking and screaming against his body and holding them there.