Master Pakku (TLA)

Legendary Creature — Human Advisor Ally

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.)

Niche tempo creature for Lessons-focused decks, but the mill effect requires heavy graveyard setup and competes with more efficient mill and tempo options in formats where it's legal.

Avatar: The Last Airbender — Uncommon