ScareGlow, for 2 reasons:
A) You can't kill what's already dead.
B) As a ghost, most things that apply to physical beings do not apply to you. (Mosquitor can't suck his blood if he doesn't have any, nor could he even if SG had blood because there's no physical point to latch on to. Snake Face can't turn him into stone because he's just a spirit. Also, if SF tried, Scare Glow'd stare right back at him and SF would be scare snakeless!)