Nanatsu no Taizai - Fundo no Shinpan - Episode 23 - The Seven Deadly Sins

Cath Palug became a troublesome opponent for Arthur but not for the Seven Deadly Sins.

Merlin and Arthur tried to take on Cath Palug by themselves but destroying a fragment of Chaos is just a philosophical category error. The arrival of the Seven Deadly Sins (Elizabeth took Escanor's place) gave Arthur space and time to realize the solution. Before then, Cath Palug showed Meliodas possible future happiness with Elizabeth and outliving all his friends. When he overcame the illusion, only he and Arthur escaped the mind trap. That was when he realized the answer was not to destroy the separate fragment of Chaos but to eat him like Cath Palug kept shouting about. Arthur absorbed Cath Palug and became the true King of Chaos. Series finale next week!