Dark Petition is a rare Sorcery card from Magic Origins (ORI), collector number 90. Current market price: $2.90 (foil $5.57), TCGplayer market prices via Scryfall.
Search your library for a card, put that card into your hand, then shuffle. Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, add {B}{B}{B}.