Chapter 754: Floor 51

Draco directly transformed into his Black Dragon True Body, roaring with majesty as his regal form stained the world with black Destruction Essence. Even the Supreme Beings in the stands went silent, shocked by what they were seeing. 

Well, you see… the Black Dragon was part of the list of Supreme Beings, along with the White Dragon. Yet somehow the motherfucker was down there fighting with the 'entertainment'. 

As you can imagine, they were horrified by the precedent this would set. It should be obvious, but once a Supreme Being was seen fighting, it would break the notion that Supreme Beings weren't allowed to fight. 

Basically, if something happened once, it broke a certain chain that prevented it from happening, so it was more likely to occur a second time, a third, until it became the norm.