I really enjoyed this. I hope that one day, when it's even more complete, you can sell this on Steam. Keep this up, and the game will be worth money. It already arguably is.
If it were up to me to add things, I would try to take advantage of the map system and deliberately make monster types that certain builds would want to avoid. Monsters with flat-rate damage reduction, where every attack has damage decreased by some constant, would very well counter those shiv builds. On the other hand, making monsters immune to the first couple attacks would discourage folks with crazy whetstone builds.