I'm trying to find a word for something that always beat something else. Kryptonite might be used for something that you always lose to. From superman of course.

i.e. Rock is scissors' kryptonite (scissors lose to rock). Water is fire's krytonite (fire loses to water), and so on.

I want to know the opposite word of this "krytonite". Say between rock and scissors. What word would be appropriate here:

Scissors are rock's _____. Fire is water's _____.