Alistair, the Brigadier (Extended Art) (WHO-401) - Doctor Who: (Extended Art) Foil

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.