The Finisher was the 5th opponent chicken Jack faced in the Creature Combat Club.
It is a large rat that is shown to be filthy and hideous. The rat usually preforms a noise that it makes with its tongue. It turns out though it is a robot in a rat costume.
The Finisher was meant to beat Jack when he was injured by Mutant Earthworm. When it came out of it dungeon like dome container it was booed because their was already an opponent fighting and releasing The Finisher was cheating.
It is unknown how the past Aku's destruction affected his existence.
Fleas: The Finisher scratches himself with his legs and arms launching dirt and fleas on the opponent.Pounce: The Finsher launches itslef at the opponent trying to bite the opponent.