Imma be real with you chief, this spellcasting system fuckin rules. I love the fact that you need to improvise your spells on the spot and that you can't use the same thing for too long, It keeps C A S T I N G S P E L L Z always fresh. If you plan to continue making something with this I recommend expanding a little on the options and refining the enemies a little, add more variety.
Another thing that might be worth experimenting with is that once a spell overheats, it doesn't go to a cooldown but its locked. In the current version, technically you can just use your op spell wombo combo until it overheats then wait until it cools down, or just jump between 2 mixes of spells. This kinda goes against the idea of forcing ppl to make up new spells so if theyre locked instead of put on a cooldown that could lead to more forced experimentation. Once a set amount of spell components have been locked every time you lock another component a random one opens up.
You could also try adding new spell options as items you can pick up to expand your arsenal, the more you find the more options you have.
Anyways, cool gaem and I see a lot of potential in a magic system like this. I found that cycling through all sorts of spells, just clicking on 3 random components and figuring out what it does while im already using it to shred some goons is incredibly fun.