I think the Pain Doll might be slightly overpowered:
Got it early, upgraded it a couple of times, and spent effectively every dollar buying items to sell for it. A 2s cooldown is absurd; maybe the pain doll is the item I should try to get to 0s cooldown. ;)
Update:
Yeah, it’s overpowered. The scaling of the amount you get for selling items is great. The scaling of the cooldown goes 8s->6s->4s->2s, and having that much damage every 4s, let alone 2s, wins a battle by itself. Even against poison. :)
That cooldown scaling is much faster than the cat, and the damage scaling is faster than the cat. I’d suggest keeping the damage scaling, and reducing the cooldown scaling so that it’s 4s at legendary and 5s at epic.