Lena, Selfless Champion is a rare Legendary Creature — Human Knight card from Core Set 2019 (M19), collector number 21. Current market price: $0.35 (foil $1.64), TCGplayer market prices via Scryfall.
When Lena enters, create a 1/1 white Soldier creature token for each nontoken creature you control. Sacrifice Lena: Creatures you control with power less than Lena's power gain indestructible until end of turn.