Love the core mechanic and the character designs and models.
VFX on attacks, both yours and enemies, would go a long way to making combat more readable and impactful. As it stands you often can't tell when or where an enemy is attacking or if your attacks will hit an enemy. The minions diving in as an atack is cool, but having like, a wooshing highlight over them when they are attacking would give a little more clarity since they mill about a lot.
You have several secret areas, but they are mostly filled with useless items. This doesn't really incentives looking for them. even just having a couple of the minion bar expansions be in the secret area would make it more interesting.
The writing has a great sense of humor and the drawn animations for the cutscenes add good personality.