Martha Jones is a rare Legendary Creature — Human Cleric card from Doctor Who (WHO), collector number 363. Current market price: $1.19 (foil $1.79), TCGplayer market prices via Scryfall.
Woman Who Walked the Earth — When Martha Jones enters, investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.") Whenever you sacrifice a Clue, Martha Jones and up to one other target creature can't be blocked this turn. Doctor's companion (You can have two commanders if the other is the Doctor.)