Appa, Steadfast Guardian + Cloud Key + Icewind Stalwart + Honest Rutstein

Appa, Steadfast Guardian

Cloud Key

Icewind Stalwart

Honest Rutstein

How it works

1. Cast Appa by paying
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.