Found a trailer showing pics from Dragon Ball Z battle of the Gods with Goku transforming into super Sayian God and landing a blow on Bills. In the information part of the page they explain how Goku reaches this stage. I shoudl tell you they are stills so don’t expect a flowing fight. The thing that is getting me is that they ask Shenron how to reach Super Sayian God but i would like to know how does the Namekin Dragon know about Super Sayian power.
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