Super Dragon Ball Heroes S01 E05 The Mightiest Warrior! Super Saiyan 4 Vegetto!!

As Goku and company are in a jam, Xeno Goku and Xeno Vegeta come to their aid, having noticed the change in the Prison Planet. To counter Cumber's bottomless power, the two use the Potara to fuse! It's the explosive birth of the mightiest warrior!