(This execution is not animated.  Unfortunately it just takes too much time and I have exams in under a week plus personal projects to get to.  Instead, I just drew a frame.  Sorry. )

Explanation: Zeben and Mononity are rowed out to sea, then locked in a cage that's sent to the bottom of the ocean. Left with a singular lockpick, Zeben quickly picks the lock and the two begin to swim to the surface. But before they can get there, a large fish emerges out of nowhere, swallowing Mononity whole. Zeben almost makes it to the surface before the fish bites him clean in half, putting an end to the class traitor.