Appa, Steadfast Guardian + Doc Aurlock, Grizzled Genius + Aang, Airbending Master

Appa, Steadfast Guardian

Doc Aurlock, Grizzled Genius

Aang, Airbending Master

How it works

1. Cast Aang by paying its mana cost.
2. When Aang enters, it triggers, airbending Appa.
3. Cast Appa from exile by paying 0 due to Doc Aurlock.
4. When Appa enters, it triggers, airbending Aang.
5. Cast Aang from exile by paying 0 due to Doc Aurlock.
6. Appa's second ability triggers, creating a 1/1 Ally creature token.
7. Repeat from step 2.

This loop relies on the seamless interplay between Appa, Steadfast Guardian, Aang, Airbending Master, and Doc Aurlock, Grizzled Genius to create a perpetual motion machine of bouncing and casting. When you cast Aang, its entry triggers the airbending of Appa, while Doc Aurlock's cost-reduction ability allows Appa—and subsequently Aang—to be recast from exile for free. As Appa and Aang continuously blink back and forth into exile and onto the battlefield, Appa's second ability fires off every time you cast a spell from exile to flood the board with infinite 1/1 white Ally creature tokens. At the same time, Aang accumulates an infinite number of experience counters as its fellow creatures repeatedly leave the battlefield without dying, ensuring a massive army of tokens on your next upkeep as well.