The Dragon Ball franchise has long since been known for its plethora of transformations, primarily the various unique forms of Super Saiyan that Goku and other heroes achieve throughout the series. The 2013 film Dragon Ball Z: Battle of Gods introduced fans to the idea of a Super Saiyan God, a transformation that has had several subsequent forms attached to it later, but the most powerful of these forms may never be seen again.
Super Dragon Ball Heroes: Big Bang Mission chapter 15 begins with Goku and company on the ropes after a drawn out battle with the new Dark King, Fu. Fu has recently absorbed the power of Dogidogi, a dark mirror to Tokitoki, a bird that controls the flow of time. It was prophesied that the appearance of Dogidogi would result in the destruction of all universes, and with Fu in control of its power this prophecy seems like it’s about to come to fruition. Fu’s ultimate plan seems to be to resurrect something called the Universe Tree and revert all time in the entire universe back to a state of zero. In order to stop him, Goku plunges himself into the Universe Tree and takes on its power, transforming into a state never before seen.
When Goku first enters the Universe Tree, Fu dismisses this idea entirely, stating it is foolish to think he won’t just be swallowed up by the Universe Tree’s immense power. Moments later, however, Fu notes that the flow of the Universe Tree has changed completely. Goku arrives back in the fight, now with the power of the Universe Tree coursing through him. This new form is officially called Super Saiyan God Super Saiyan (Universe Tree Power). Due to the unique circumstances that allow Goku to achieve this state of Super Saiyan God, it’s likely his most powerful transformation ever and also will likely never appear again.
Dragon Ball Heroes as a whole attempts to explore the Dragon Ball macroverse as well as multiple timelines, and as a result the stakes of each story are always on a larger than life, universal scale. Due to this, every transformation or character featured within these stories needs to be at that universal level of fighting power in order to remain relevant within the series itself. Goku is no exception, and Dragon Ball Heroes proves that it’s willing to give Goku literally any power up possible in order to make sure he saves the day. Goku bearing the power of the Universe Tree is possibly the greatest feat of strength ever as it takes Beerus’ entire reserve of power in order to stop the Universe Tree’s roots from spreading throughout the universe. Without a doubt, in this form Goku surpasses the Gods of Destruction and is more than likely closer to an angel in power than ever before.
Because of this form’s completely overwhelming power and the required presence of the Universe Tree in order to use it, this Super Saiyan God Super Saiyan (Universe Tree Power) form will likely never be seen again. Even though Dragon Ball’s Dragon Ball Heroes has a habit of bringing back old transformations to play up the nostalgia factor, it would be far too convenient for this variation of Goku’s Super Saiyan God form to ever return.