Kaya the Inexorable + Ugin's Nexus + Karn, the Great Creator + Carrion Feeder

Kaya the Inexorable

Ugin's Nexus

Karn, the Great Creator

Carrion Feeder

How it works

1. Activate Karn's first loyalty ability by putting a loyalty counter on it, causing Ugin's Nexus to become an artifact creature until end of turn.
2. Activate Kaya's first loyalty ability by putting a loyalty counter on it, putting a ghostform counter on Ugin's Nexus.
3. Activate Carrion Feeder by sacrificing Ugin's Nexus.
4. Ugin's Nexus is exiled instead of being put into your graveyard, causing you to take an extra turn after this one.
5. Ugin's Nexus triggers, returning itself from exile to your hand, and creating a 1/1 Spirit creature token.
6. Resolve the Carrion Feeder ability from step 3, putting a +1/+1 counter on it.
7. Move to your next turn.
8. Cast Ugin's Nexus by paying 5.
9. Repeat.