Oh yeah I felt the strategy of basically saving up heals, however on my 2 runs I would use heal on turn one (if I drew them at all) and then spam my damage spells on a single target. I felt that if I seeded my deck with only damage and never leveled up healing, then it wouldn't matter if the heals missed because the enemy would be dead. It was a glass cannon approach but it got me up to the ghoul with 2 skeletons at least.
If you consider developing this idea further, I think a lot of the trouble will be balancing the experience. The other issue is the massive influx of card based deck building roguelikes games on steam. You'd be in stiff competition with everyone, including granddaddy Slay the Spire.
There is so much creative room for new spells and flavor, but honestly good job!