Ozox, the Clattering King + Phyrexian Altar + Totentanz, Swarm Piper

Ozox, the Clattering King

Phyrexian Altar

Totentanz, Swarm Piper

How it works

1. Activate Phyrexian Altar by sacrificing Ozox, adding 1.
2. When Ozox dies, it and Totentanz trigger.
3. Resolve the Ozox trigger, creating a legendary 2/1 Jumblebones creature token.
4. Resolve the Totentanz trigger, creating a creature token.
5. Activate Phyrexian Altar twice by sacrificing Jumblebones and the other creature token, adding 1.
6. When Jumblebones dies, it triggers, returning Ozox from your graveyard to your hand.
7. Cast Ozox by paying 2.
8. Repeat.