Keen-Eared Sentry is a uncommon Creature — Human Soldier card from Adventures in the Forgotten Realms (AFR), collector number 22. Current market price: $0.22 (foil $0.30), TCGplayer market prices via Scryfall.
You have hexproof. (You can't be the target of spells or abilities your opponents control.) Each opponent can't venture into the dungeon more than once each turn.