Lulu, Stern Guardian is a rare Legendary Creature — Human Wizard card from Final Fantasy Commander (FIC), collector number 143. Current market price: $2.71 (foil $13.31), TCGplayer market prices via Scryfall.
Whenever an opponent attacks you, choose target creature attacking you. Put a stun counter on that creature. {3}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)