Anowon, the Ruin Thief is a mythic Legendary Creature — Vampire Rogue card from Secret Lair Drop (SLD), collector number 1568. Current market price: $2.86, TCGplayer market prices via Scryfall.
Other Rogues you control get +1/+1. Whenever one or more Rogues you control deal combat damage to a player, that player mills a card for each 1 damage dealt to them. If the player mills at least one creature card this way, you draw a card. (To mill a card, a player puts the top card of their library into their graveyard.)