Up until the end of Dragon Ball’s original run, the pinnacle of Saiyan power was thought to be Super Saiyan 3. The release of Dragon Ball GT changed this by introducing Super Saiyan 4, and this remained the strongest Saiyan transformation for a little over a decade. When Dragon Ball Super was announced, and God transformations became the status quo for Saiyan power, Super Saiyan 4 was altogether abandoned… that is, until the release of Dragon Ball Heroes. Dragon Ball Heroes took Super Saiyan 4 a step further with Xeno Goku and Vegeta and proved once and for all that there is more power in what lies beyond.
Even though Dragon Ball GT ended with Super Saiyan 4 at the top of the Super Saiyan hierarchy, there were hints that something lay beyond its power. When Goku and Vegeta battle Omega Shenron towards the end of the series, they both acknowledge that their powers alone are not strong enough and decide to fuse. Super Saiyan 4 Gogeta was a peerless fighter when first introduced, and his strange appearance may have hinted at a separate Super Saiyan 4 transformation. Dragon Ball Heroes offers an explanation for this change as well as a glimpse of the power that surpasses Super Saiyan 4.
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In chapter 3 of Super Dragon Ball Heroes: Big Bang Mission, Xeno Goku and Vegeta face off against Dark Janemba, a version of the demon that has been upgraded to match their base Super Saiyan 4 power. This ruthless foe proves to be far too powerful to deal with at their current level, beating Goku and Vegeta easily. Trunks, Pan, as well as Goku and Vegeta from the main timeline, offer to give their energy to Xeno Goku in order to stop Janemba but Xeno Vegeta argues with
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