Great use of the theme, and really fun! Ended up playing for too long, because I wanted to see how strong I could make my wind spell, lol! It's great that you can feel the progression of becoming stronger, and it seems that some monsters are more resistant to some types of spells, which is a nice touch. I think it also have a lot of potential for further development.
That said, I think it could use some more polish in the graphical department. Also, potions for healing, and stronger monsters in the next levels! Otherwise, great job!