Brotherhood Outcast + Shade's Form + Yahenni, Undying Partisan

Brotherhood Outcast

Shade's Form

Yahenni, Undying Partisan

How it works

1. Activate Yahenni 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 Yahenni ability.
5. Repeat.