Primeval Spawn + Chorus of the Conclave + Mortuary + Phyrexian Altar

Primeval Spawn

Chorus of the Conclave

Mortuary

Phyrexian Altar

How it works

1. Activate Phyrexian Altar by sacrificing Primeval Spawn, adding 1.
2. When Primeval Spawn dies, its second ability and Mortuary trigger.
3. Resolve the Mortuary trigger, putting Primeval Spawn on top of your library from your graveyard.
4. Resolve the Primeval Spawn trigger, exiling the top ten cards of your library, and casting Primeval Spawn by paying a total of 1 due to Chorus of the Conclave.
5. Repeat.