I really really appreciate the elaborate feedback. When we first thought about making a one turn kill game, the problem was that each battle could end up being the same, making the game boring and grindy. We had to figure out a way to make the decisions more interesting. Then we decided to make multiple spells and have the gameplay be similar to something like 'Slay the Spire' with spell synergies etc. This created more interesting decision making to the game but did not solve the problem of having each battle be the same. That's how we arrived at the final mechanic of having the spells be one time use. It was apt that the process of selecting the spells was as 'tense' (if it can be called that) as being killed by a giant primordial in one turn.
Though, I must admit the final product fell short of our aim by quite a bit. I will work on the UI a great bit. Have received multiple suggestions about what could use improvement. I hope you'll try out the next iteration of our game when it comes out.