The Super Hero Squad Show S01 E14 Tremble at the Might of M.O.D.O.K.!

When M.O.D.O.K. gains the power of an Infinity Fractal, he robs Dr. Doom of his powers and takes over as leader. Loki learns of this and decides to ally himself with M.O.D.O.K., forcing Dr. Doom to join forces with the Super Hero Squad in order to defeat M.O.D.O.K. and reclaim his rightful place as leader.