Would be nice if the cost of potions and jewels reset after every ascend, you could increase more the price after every buy but reset after ascend.
Jewels having a expendable charge while the price keep increasing is quite bad imo.
The extra exp/gold gem could be changed to be % instead of a flat amount, because the way its now, its easier to level and farm gold on low hp enemies that you can 1 shot.
The study could be changed to talent points that you get after every some levels, because standing there doing almost "nothing" wont make the game any extra fun, or you could change it to "training" and passively get exp on it as you still kill enemies.
Other than that theres a few other things, but for now i guess this is alright.