Hold the Perimeter is a rare Conspiracy card from Conspiracy: Take the Crown (CN2), collector number 6. Current market price: $0.13 (foil $0.85), TCGplayer market prices via Scryfall.
(Start the game with this conspiracy face up in the command zone.) At the beginning of your first upkeep, create a 1/2 white Soldier creature token with defender. At the beginning of each other player's first upkeep, that player creates a 1/1 red Goblin creature token with "This token can't block."