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

Prerequisites

• Zinnia, Valley's Voice on the battlefield
• Appa, Steadfast Guardian in hand
• Priest of Urabrask in hand
• Panharmonicon on the battlefield
• available

Steps

1. Cast Priest of Urabrask by paying its mana cost plus an additional 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 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 plus an additional for its offspring cost
17. Repeat steps 2 through 6 once
18. Cast Appa from exile by paying plus an additional for its offspring cost
19. Repeat from step 8

Results

• Infinite ETB
• Infinite LTB
• Infinite blinking of nonland permanents
• Infinite creature tokens
• Infinite red mana
• Infinite storm count