Forget about the "who" will kill him, just get to the "how".
Will he get stabbed through the heart in a cliche fashion? Decapitated by some outrageous oversize sword? Blown to bits by magic? Shot in the head? Will Garrosh feel guilty at the very end and kill himself? Will somebody grapple his skull and sheer it out of Garrosh's body and his spinal cord along with it?
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