Piper of the Swarm is a rare Creature — Human Warlock card from Forgotten Realms Commander (AFC), collector number 106. Current market price: $2.25, TCGplayer market prices via Scryfall.
Rats you control have menace. {1}{B}, {T}: Create a 1/1 black Rat creature token. {2}{B}{B}, {T}, Sacrifice three Rats: Gain control of target creature.