Vigilant Sentry is a common Creature — Human Nomad card from Dominaria Remastered (DMR), collector number 33. Current market price: $0.04 (foil $0.11), TCGplayer market prices via Scryfall.
Threshold — As long as there are seven or more cards in your graveyard, this creature gets +1/+1 and has "{T}: Target attacking or blocking creature gets +3/+3 until end of turn."