It looks great, but currently doesn't fit for Mob Arena. The map has to be a square, the walls have to be unbreakable and there needs to be no camping places. I can see some houses, bridges, and mountains there. Mob Arena seems "vanillary???" because it needs to be simple so people don't end up abusing it. The Moon arena suffered many changes until it was released because of that.
If you were making this map for server use, maybe it can be used for something else in the future, such as Paintball or possibly Hide and Seek, if it ends up possible doing that Minigame.