-Element orbs disappear behind walls and other decoration, which sometimes look bad. Walls especially because on the vertical ones they appear and disappear on the seams of said wall tiles.
-As they are, the cave levels feel a bit sparse.
-No feedback when you can't buy something in the shop, or when you don't have enough mana to cast a spell.
-Option of up to two spells depending on last 3 orbs is nifty. Also, so far double umbra is quite powerful, you can just shoot through walls with it. [later] or I guess it's not unique, a lot of spells go through walls.
-Map screen shows your options, but not the path you took to get there. Not important, but would be nice to have.
-You can't cast a spell with only 2 orbs, which is kind of weird. By the logic presented, I should be able to.
-Beat da game. Not much to it, but it's decently fun. Could use type effectiveness against monsters to better incentivize switching the spells up?
Keep up the good work.