Alistair, the Brigadier is a rare Legendary Creature — Human Soldier card from Doctor Who (WHO), collector number 717. Current market price: — (foil $1.56), TCGplayer market prices via Scryfall.
Whenever you cast a historic spell, create a 1/1 white Soldier creature token. (Artifacts, legendaries, and Sagas are historic.) Whenever Alistair attacks, you may pay {8}. If you do, creatures you control get +X/+X until end of turn, where X is the number of historic permanents you control.