Rakdos Joins Up is a rare Legendary Enchantment card from Outlaws of Thunder Junction Promos (POTJ), collector number 225p. Current market price: $0.65 (foil $0.82), TCGplayer market prices via Scryfall.
When Rakdos Joins Up enters, return target creature card from your graveyard to the battlefield with two additional +1/+1 counters on it. Whenever a legendary creature you control dies, Rakdos Joins Up deals damage equal to that creature's power to target opponent.