Ey, I just tried your game!
It has some good artwork, despite looking unpolished.
The mechanic itself is charming and really appealing. Not many games do the "draw to cast spell" idea and yours works it in almost effortlessly as a primary mechanic, which is done through being really simple. No muddling through spells to find the right one or having to speed draw, just aim where the boss is going to be, bait them into it, draw and let go when they're there!
Genuinely fun, I'd like to see this developed further.
HMU if you need any advice or need someone to test! ^^
Discord: peterstubbs
Twitter: @PeterStubbsVG