Corrupted Conscience is a uncommon Enchantment — Aura card from The List (PLST), collector number MBS-22. Current market price: $0.84, TCGplayer market prices via Scryfall.
Enchant creature You control enchanted creature. Enchanted creature has infect. (It deals damage to creatures in the form of -1/-1 counters and to players in the form of poison counters.)