X-Men: Evolution - Season 2 Episode 17

The Brotherhood/X-men arrive where Magneto is with his new allies, but Quicksilver suddenly reveals he is part of Magneto's team. The others begin to battle the allies, but without warning, Magneto caves in the ground, and a mega-robot sentinel is released. The government agents with the sentinel trap a few members of the team, and the remaining retreat back to the destructed institute. Scott and the other students explain how they escaped then Scott suddenly accuses the Professor of setting it up. Professor X suddenly morphs into Mystique, shocking them all, stating that "Things are about to get much worse...."