I can't remember what level I was. I do remember I had to reload once because I'd tricked him into consuming a wrong sphere and after that Linu wouldn't cast the harm I'd been counting on (appearantly she thought he didn't have enough HP left for the spell to be worth it. Leave the thinking to me, Linu
). On the second go he didn't get the sphere (although I might have given him a correct one if I'd had a previous save) and it worked out just fine. Conclusion:
Trickses don't always work.