March of Wretched Sorrow is a rare Instant card from Kamigawa: Neon Dynasty Promos (PNEO), collector number 111p. Current market price: $0.64 (foil $0.75), TCGplayer market prices via Scryfall.
As an additional cost to cast this spell, you may exile any number of black cards from your hand. This spell costs {2} less to cast for each card exiled this way. March of Wretched Sorrow deals X damage to target creature or planeswalker and you gain X life.