Master Pakku is a uncommon Legendary Creature — Human Advisor Ally card from Avatar: The Last Airbender (TLA), collector number 63. Current market price: $0.11 (foil $0.24), TCGplayer market prices via Scryfall.
Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.) Whenever Master Pakku becomes tapped, target player mills X cards, where X is the number of Lesson cards in your graveyard. (They put the top X cards of their library into their graveyard.)