Abyssal Nocturnus is a rare Creature — Horror card from Guildpact (GPT), collector number 43. Current market price: $0.69 (foil $2.81), TCGplayer market prices via Scryfall.
Whenever an opponent discards a card, this creature gets +2/+2 and gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)