Treacherous Pit-Dweller is a rare Creature — Demon card from Avacyn Restored (AVR), collector number 121. Current market price: $0.34 (foil $1.17), TCGplayer market prices via Scryfall.
When this creature enters from a graveyard, target opponent gains control of it. Undying (When this creature dies, if it had no +1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)