Hellooo!
I tried the game a tiny bit and here are some things to think about if you wanna?
When it comes to the arena as SnakenBacon said the temporary buffs are not appetizing at all when you compare them to the permanent ones.
The game lacks in interactivity, by that I mean something that you do that significantly changes the playstate, perhaps you could think of adding different attacks or skills like a jump or a shield as SnaconBacon already suggested
Last thing I'd like to bring up is that I have no idea how I'm supposed to interact with the game outside of the arena and have no clue what's supposed to be the fun part of it, so you can think of either a tutorial or just some better communication around that. (I dunno if you attended the OODA loop talk but I think it could potentially help with somethings, it is a pretty good tool imo)
Either way thanks for working hard and making a cool thing!!!