Too bad I can't make it through the first wave!
I read on one of your responses that the slot machine select randomly your spell, but with just one. Maybe make your player actively stopping it, to influence damages too (like the first column is the spell, and th second and third will boost or nerf your damages depending of the difference with the first?)
For poison/burn status, you can i think pick the one from Slay the Spire (where poison damage is how many turns it has left), to make it interesting to stack
Need a little bit of balancing between health and mana management, because heal isn't worth currently (tried to spam heal then mana regen, and was losing hp at the end
Your concept has potential, it just needs some more work to be really fleshed out!
Have fun making games, it's always a succes when you sucess on building one!