User blog comment:AnonymousAK/Demon's Royale/@comment-7418318-20140715142255

In this situation Franmalth is probably a major game-breaker. All his opponents use magic, which he can absorb. And if they try to attack him in close combat, he can absorb them. Kain might have the necessary physical prowess to pull a similar stunt like Natsu, but since he's rathe dumb he would need someone else to figure that trick out for him and order him around.

Capricorn would also be a major problem for the OS. With his Human Subordination Magic he could easily deal with the other four (minus Brain as stated in the blog) OS members and have either his summons keep Angel at bay or watch the other members of the Seven Kin gang up on her.

As MrGW said, Sayla would also be a massive problem for her enemies since she could just pick out the most troublesome enemy and simply use him or her as her own weapon. If she uses this victim in a way that quickly exhausts them to the point of no longer being able to fight, she could wear out one after the other until noone is left to oppose them.