How about..........convincing him what he's doing is wrong?
Similarly, you could turn it on itself or redirect it, perhaps by convincing it that another target is the real threat, rendering it ineffective via insanity or in the former case by convincing it to target itself. Depending on your setting and Big Bad, this could involve illusions, mind control, reprogramming, hallucinatory illness, psychology, lies, misleading spacetime geometry or even Gaslighting
(for patient heroes).
edited 24th Mar '12 6:12:25 PM by ArsThaumaturgis