Phyrexian Altar + Feign Death + Repository Skaab + Necroduality

Phyrexian Altar

Feign Death

Repository Skaab

Necroduality

How it works

1. Cast Feign Death by paying , targeting Repository Skaab.
2. Activate Phyrexian Altar by sacrificing Repository Skaab, adding .
3. When Repository Skaab dies, it triggers, returning it from your graveyard to the battlefield.
4. When Repository Skaab enters the battlefield, its exploit ability and Necroduality trigger.
5. Resolve the Necroduality trigger, creating a token copy of it.
6. When the Repository Skaab token enters the battlefield, its exploit ability triggers; choose not to sacrifice a creature.
7. Resolve the Repository Skaab trigger from step 4, sacrificing the Repository Skaab token.
8. Repository Skaab's second ability triggers, returning Feign Death to your hand from your graveyard.
9. Repeat.