Possessed Aven is a rare Creature — Bird Soldier Horror card from Torment (TOR), collector number 45. Current market price: $0.29 (foil $3.70), TCGplayer market prices via Scryfall.
Flying Threshold — As long as there are seven or more cards in your graveyard, this creature gets +1/+1, is black, and has "{2}{B}, {T}: Destroy target blue creature."