Zinnia, Valley's Voice + Appa, Steadfast Guardian + Priest of Urabrask + Panharmonicon

Zinnia, Valley's Voice

Appa, Steadfast Guardian

Priest of Urabrask

Panharmonicon

How it works

1. Cast Priest of Urabrask by paying its mana cost plus an additional 2 for its offspring cost.
2. When Priest of Urabrask enters, it triggers twice and its offspring ability triggers twice due to Panharmonicon.
3. Resolve both innate Priest of Urabrask triggers, adding six .
4. Resolve the first offspring trigger, creating a token copy of Priest of Urabrask that is 1/1.
5. When the Priest of Urabrask token enters, it triggers twice, adding six .
6. Repeat steps 4 and 5 for the remaining offspring trigger.
7. Cast Appa by paying its mana cost plus an additional 2 for its offspring cost.
8. When Appa enters, it triggers twice and its offspring ability triggers twice.
9. Resolve both innate Appa triggers, airbending the nontoken Priest of Urabrask.
10. Resolve the first offspring trigger, creating a token copy of Appa that is 1/1.
11. Put the Appa token into your graveyard due to the legend rule.
12. The Appa token's enter-the-battlefield ability triggers, airbending nothing.
13. Resolve the second offspring trigger, creating a token copy of Appa that is 1/1.
14. Put the Appa token into your graveyard due to the legend rule.
15. The Appa token's enter-the-battlefield ability triggers, airbending the nontoken Appa.
16. Cast Priest of Urabrask from exile by paying 2 plus an additional 2 for its offspring cost.
17. Repeat steps 2 through 6 once.
18. Cast Appa from exile by paying 2 plus an additional 2 for its offspring cost.
19. Repeat from step 8.

This intricate loop transforms Zinnia, Valley's Voice into an engine of endless multiplication by granting offspring to everything you cast. The real magic happens when Panharmonicon doubles every entry trigger, allowing Priest of Urabrask to flood your pool with massive amounts of red mana. Meanwhile, Appa, Steadfast Guardian leverages this mana to airbend your permanents into exile, and its secondary ability rewards you with 1/1 Ally tokens whenever those exiled spells are cast. By continuously re-casting both creatures from exile while the legend rule neatly recycles duplicate Appas, you generate an unstoppable cascade of creature entries, tokens, and mana.