Tonton Streaming The Super Hero Squad Show (2009) S1E13 - Deadly is the Black Widow's Bite!

After helping the Super Hero Squad in a battle against Screaming Mimi, Abomination and M.O.D.O.K., Black Widow joins the team. However, unknown to them, she is actually Mystique in disguise sent by Dr. Doom to steal the Infinity Fractals from the Vault.