The music is soo good! Makes the game really intense, i love it. The art style is also really cool. I would genuinely enjoy playing this game regularly if you made a couple fixes. For example, a narrative aspect would help as I dont understand what exactly Im doing, what am I protecting or attacking? There also doesnt seem to be any consequences for just leaving the spiders and sitting back to watch them attack. It also doesnt look like any of my hits are actually doing anything... That being said, some quick, easy fixes can make this game really really great :))

I tried everything but I was unable to cast any spells. I tried pressing all the spell buttons, combinations of the spell buttons, left clicking at different times. What am I missing?

I enjoyed our concept reminded me somewhat of Magicka.
Props to you for including Settings menu with a lot of settings.
Maybe you could introduce some limitation on the casting of the spell so that spam spell casting isn't so powerful anymore and the emphasize is more on clever choosing of the combination of spells.

All in all I enjoyed this short experience, good job :D