Circle arenas...

[Nalien]

Sorry, but this was also a circle arena.

It had multiple levels, that's what's important. You didn't just fight Darnus in the same circle; you sent ranged onto the stairs to take out comets, and DPS up to the very top to finish zerging him (or whatever, it's been a while). Much more interesting than the current arena designs, in my opinion.

I mean really, compare the two (Coil Turn 9 spoilers yo);