The concept was neat, but the UI really hurt the gameplay. Having to go back over to the whel to turn it, but needing to also use the mouse to aim was a lot of back and forth that doesn't work well for a fast paced combat game. There was also a comment about attacking with one spell makes others faster, implying the intent that you often switch. The biggest improvement, I think, would be to allow the right mouse to be able to rotate the selection from anywhere. It might even be worth making it a simpler right click and drag left or right a certain distance to simply move all the way to the next slot, instead of slowly rotating and having it part way between 2 options. It is nice that there is an indication when it changes, but having it solidly center would be good. I would have changed abilities more often if not for the delay, especially when enemies were on the left side. You could favor going left to keep many enemies on the right and reduce time to change things, but then the UI for it gets in the way of seeing them. Down left to keep enemies to the top right is an option, but does limit gameplay choices. However you do it, I really think this could use some work to improve the enjoyment of the game.
The simple shapes and colors worked for the game. The different attacks were nice and had enough differences to be worth switching, even though the switching meant racing the mouse over and back. The initial instructions were clear enough to quickly get you playing.