Tinybones Joins Up is a rare Legendary Enchantment card from Outlaws of Thunder Junction (OTJ), collector number 328. Current market price: $2.95 (foil $4.49), TCGplayer market prices via Scryfall.
When Tinybones Joins Up enters, any number of target players each discard a card. Whenever a legendary creature you control enters, any number of target players each mill a card and lose 1 life.