really love the game, played an hour : )
I think it would be cool with like an ice mob that made the floor slippery, or variated blue or purple slimes who make the floor sticky so it slows. Since movement is the main mechanic, it feels relevant to challenge it!
I also started imagining something like a "mariokart questionmark", which might be a debuff or an enemy reroll, but could also be a 2-3 second buff for attack speed or a single use spell, like the dash, that you can use up, with spacebar. It could be potions or elixirs of different colors.
I think that might make it more unpredictable, wacky even : )