and let players be the "cleaners" of instances by killing bots for fun and profit.
Bot kills the mini-boss/npc 5 times in 5 spawns (or use a simple algo), bot is flagged for pvp or the instance. Bots will then either kill each other over and over or players will be able to kill bots.
If you are a legitimate player farming the boss/miniboss you can do that 5 times then you get a mini game like the chest to prove you are human. If you solve it your counter gets reset so no risks to be griefed.
Step 3: Profit