A very interesting idea! I especially like the tetris-style of the game, it attracts attention :)
Couple of points that I;d like to comment on:
- I didn't immediately catch that you can rotate the spells only as you are holding them — after reading the instructions it seemed that I could do it after placing the spells on the board;
- There is a possibility to end your turn without attacking — I am not sure that you would ever need that, or did I understand something wrong? Maybe the "End Turn" button should be inactive until you've used all your spells :)
- It is also not immediately clear that you should click your spells after confirming the grid, though it is written in caps :D Maybe I was not very attentive, or maybe it is because the "End Turn" button attracts much more attention than the text, so yo get that urge to click it as soon as you confirmed everything.
- I really enjoyed the tetris grid and the idea looks promising! But I am not sure that it gave me any additional challenge. I just placed everything I could there and clicked without following any certain strategy and everything went well for me :D It would be great if the grid made me think harder and choose which spells I am going to use, leaving some possibility for failure if I did a wrong move, for example :)
- Regarding the UI — the "Next spell" field is located under the picture of your opponent and intuitively it feels like it is their spell, but not yours. It would probably a bit more convenient to have this information closer to your portrait, somewhere on the left,
I wish you luck with the game! Pretty sure that with more spells and just a bit more order on the "battle field" it will feel awesome :)