Appa, Steadfast Guardian + Heartless Summoning + Aang, Airbending Master

Appa, Steadfast Guardian

Heartless Summoning

Aang, Airbending Master

How it works

1. Cast Appa by paying .
2. When Appa enters, it triggers, airbending Aang.
3. Cast Aang from exile by paying 0.
4. Appa triggers, creating a 1/1 Ally creature token.
5. When Aang enters, it triggers, airbending Appa.
6. Cast Appa from exile by paying 0.
7. Repeat from step 2.

This loop uses Heartless Summoning to reduce creature costs by {2}, allowing both Appa, Steadfast Guardian and Aang, Airbending Master to be recast from exile for free whenever they are airbent away. When Appa enters the battlefield, it exiles Aang, and when Aang returns the favor, Appa's triggered ability rewards you with a steady stream of 1/1 white Ally creature tokens while sending Aang right back into exile. At the same time, Aang accumulates experience counters whenever your creatures leave the battlefield without dying, scaling your token production at the beginning of each upkeep.