Very great game! I found it to be really compelling from the start
The only game design issue I found is that the fire spell is super over powered compared to the rest, so kind of a balancing issue. The thunder is super hard to hit, kind of requiring you to mark enemies with your hand, which make you lose time. I was trying to vary spells and lost some levels, until I started to just use fire all the time, it is strong and have a big AoE. This changed the game, because now the levels got more monotonous and I was just spamming fire around the region with enemies.
I think the game would remain super compelling if it had enemies that was strong against some kind of spell, like coal miners with a fire resistant suit, a rubber guy that resist electricity and a guy with a huge hammer that could break walls, this would mean I would have to vary spells and counter them in specific ways, and not just spam no matter what enemies comes.
The writing works really well, but I was curious to try a version in which you write in the ground itself instead of having this layer of 'positional transformation'. It might be fun test and feel if the game gets better or worse, and which direction the project would grow based on this change.
Anyway, great game, congratulations! Hope this feedback helps you guys :)