Appa, Steadfast Guardian + Umori, the Collector + Restoration Angel + Grand Arbiter Augustin IV

Appa, Steadfast Guardian

Umori, the Collector

Restoration Angel

Grand Arbiter Augustin IV

How it works

1. Cast Appa by paying
2. When Appa enters, its first ability triggers, exiling Restoration Angel with the ability to cast it later from exile.
3. Cast Restoration Angel from exile by paying 0.
4. Appa's second ability triggers, creating a 1/1 Ally creature token
5. When Restoration Angel enters, it triggers, blinking Appa.
6. Repeat from step 2.