Assassins

After his initial win, Kretos kept on winning in the underground fighting ring. He won all the battles in such an overwhelming manner that the name of Kretos the killer of a thousand demons spread throughout the western lands. His name drew in the most powerful demons in the western lands. Yet no matter who he faced Kretos would win, as victory seems to be his and his alone. 

The one assigned to watch Kretos already understood that fighting with Kretos head-on without the power equivalent to a demon lord was foolish. Yet he wasn't expecting that Kretos would be this powerful. Every time Kretos fought he would always allow his opponent to attack at full power, and Kretos would happily accept everything. When the opponent showed everything he had Kretos would then retaliate and only use the minimum strength needed to beat his opponents.