Monstrous has his name for a reason.
He creates mixed up creatures by combining parts and weapons.
Monstrous has, with his years of experimenting on himself, finally mastered the art of poisons. He had attached filaments to his back that all release a different toxin, if he releases one and another one they mix and set off an explosion, or more powerful toxin. He can combine these toxins to create and steal whatever he wants.