Brotherhood Outcast + Spawning Pit + Shade's Form

Brotherhood Outcast

Spawning Pit

Shade's Form

How it works

1. Activate Spawning Pit by sacrificing Brotherhood Outcast.
2. When Brotherhood Outcast dies, Shade's Form triggers, returning Brotherhood Outcast from your graveyard to the battlefield.
3. When Brotherhood Outcast enters the battlefield, it triggers, returning Shade's Form from your graveyard to the battlefield attached to Brotherhood Outcast.
4. Resolve the Spawning Pit ability.
5. Repeat.