Hey mate, I like the concept but the arena itself will be "on the ground" which will have different skins. I realize I didn't make it easy in my post to understand but you're quite close with the idea.
Other than that it will only be 1v1 creature vs creature and healer vs healer, not 2v2 creatures.
So the arena basically has to blend together while let's say 80% of the "inside" of the half circle represents the class.
Feel free to ask if anything's unclear!
hmmmm
okay i think i have more ideas that i can sketch up from your explanation