Hi there. Figured I'd post officially since I need to do so sooner or later.
I guess I shouldn't spoil the plan, but I've got one in mind that should integrate well with the map regardless of how the layout is. It'd work best if the entrance to the arena is on the edge of the map, though, to ensure that there's enough space, since I may have to cheat and design the enemy+fight in advance since 3 days is pretty short if custom sprites are to be involved.
I also said I'd shy away from phases 2 and 3, but I won't rule myself out of the possibility completely. I could fill in with some visual/gameplay tightening if need be, though I'll let that be addressed when the time comes. If enough takers arrive so that there's no need for my tinkering, that's all the merrier.