Jamie McCrimmon is a rare Legendary Creature — Human Warrior card from Doctor Who (WHO), collector number 105. Current market price: $0.22 (foil $0.39), TCGplayer market prices via Scryfall.
Trample Whenever you cast a historic spell, Jamie McCrimmon gets +X/+X until end of turn, where X is that spell's mana value. (Artifacts, legendaries, and Sagas are historic.) Doctor's companion (You can have two commanders if the other is the Doctor.)