User blog comment:Jkphantom9/Volume 3 Episode 6 Preview/@comment-26397825-20151210024628

About the biomes; If you look closely at the background behind Mercury when he says "You wish", you can actually see that they are fighting in the centre part of the arena. The centre is actually raised, floating level with the lowest seats in the stands, and the outer areas that usually disappear to put the biomes in place are still in the background, just at ground level.