Lena, Selfless Champion is a rare Legendary Creature — Human Knight card from Jumpstart (JMP), collector number 117. Current market price: $0.38, 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.