Appa, Steadfast Guardian + Semblance Anvil + Icewind Stalwart

Appa, Steadfast Guardian

Semblance Anvil

Icewind Stalwart

How it works

1. Cast Appa either from your hand or from the command zone by paying plus commander tax, if applicable.
2. When Appa enters, its first ability triggers, exiling Icewind Stalwart with the ability to cast it later from exile.
3. Cast Icewind Stalwart from exile by paying 0.
4. Appa's second ability triggers, creating a 1/1 Ally creature token.
5. When Icewind Stalwart enters, it triggers, blinking Appa.
6. Repeat from step 2.

This looping engine relies on Appa, Steadfast Guardian and Icewind Stalwart continuously blinking each other to generate an endless stream of triggers. The trick is made possible by Semblance Anvil, which imprints a card of the appropriate type to slash the casting cost of Icewind Stalwart down to zero, completely removing the mana barrier that would otherwise halt the loop. Every time Appa, Steadfast Guardian airbends Icewind Stalwart into exile, you can immediately cast it for free, which in turn triggers Appa's second ability to flood the board with an endless army of 1/1 white Ally creature tokens while driving your storm count through the roof.