Desperate Sentry is a common Creature — Human Soldier card from Eldritch Moon (EMN), collector number 21. Current market price: $0.18 (foil $0.30), TCGplayer market prices via Scryfall.
When this creature dies, create a 3/2 colorless Eldrazi Horror creature token. Delirium — This creature gets +3/+0 as long as there are four or more card types among cards in your graveyard.