Assassin's Ink is a uncommon Instant card from Kamigawa: Neon Dynasty (NEO), collector number 87. Current market price: $0.20 (foil $0.25), TCGplayer market prices via Scryfall.
This spell costs {1} less to cast if you control an artifact and {1} less to cast if you control an enchantment. Destroy target creature or planeswalker.