I Need an Auto-battle System that can rapidly simulate the battle

Hello! I am making a small game about crafting over powered weapons.

The core loop is: You are the black smith, and you make weapons. Your team of adventurers take them into the arena, battle as long as they can, and are given rewards depending how many waves they defeat.

You use the supplies to craft stronger and stronger weapons, locking the best modifiers, and continue to push the limits.

I need an auto-battle system that can simulate pushing the floors previously completed with weaker weapons, and creating more and more difficult floors for the new weapons to challenge.

Would love to see peoples work. I don't actually need this to be a well animated high graphic feature. It's mostly just a small video that plays out between crafting sessions.