Samwise the Stouthearted + Nim Deathmantle + Ashnod's Altar + Ornithopter

Samwise the Stouthearted

Nim Deathmantle

Ashnod's Altar

Ornithopter

How it works

1. Activate Ashnod's Altar by sacrificing Ornithopter, adding CC.
2. When Ornithopter dies, Nim Deathmantle triggers, choose not to pay for the trigger.
3. Activate Ashnod's Altar by sacrificing Samwise the Stouthearted, adding CC.
4. When Samwise the Stouthearted dies, Nim Deathmantle triggers, causing you to pay 4 to return Samwise the Stouthearted from your graveyard to the battlefield, and attach Nim Deathmantle to it.
5. When Samwise the Stouthearted enters the battlefield, it triggers, returning Ornithopter from your graveyard to your hand, and causing the Ring to tempt you.
6. Cast Ornithopter by paying 0.
7. Repeat.