Cast Graceful Reprieve by paying its mana cost.
Holding priority, cast Dualcaster Mage by paying its mana cost.
When Dualcaster Mage enters, it triggers, copying Graceful Reprieve, with the copy targeting Dualcaster Mage.
Resolve the copy of Graceful Reprieve.
Holding priority, activate Ashnod's Altar by sacrificing Dualcaster Mage.
When Dualcaster Mage dies, Graceful Reprieve triggers, returning Dualcaster Mage from your graveyard to the battlefield.
Repeat from step 3.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite colorless mana

Infinite magecraft triggers

Ashnod's Altar

Graceful Reprieve

Dualcaster Mage

Cast Graceful Reprieve by paying {W}, targeting Eternal Witness.
Activate Phyrexian Altar by sacrificing Eternal Witness, adding {W}.
When Eternal Witness dies, Graceful Reprieve triggers, returning Eternal Witness from your graveyard to the battlefield.
When Eternal Witness enters the battlefield, it triggers, returning Graceful Reprieve from your graveyard to your hand.
Repeat.

Infinite storm count

Phyrexian Altar

Cloud Key

Eternal Witness

Cast Graceful Reprieve by paying {W}, targeting Archaeomancer.
Activate Phyrexian Altar by sacrificing Archaeomancer, adding {W}.
When Archaeomancer dies, Graceful Reprieve triggers, returning Archaeomancer from your graveyard to the battlefield.
When Archaeomancer enters the battlefield, it triggers, returning Graceful Reprieve from your graveyard to your hand.
Repeat.

Archaeomancer

Cast Graceful Reprieve by paying {W}, targeting Living Lightning.
Activate Phyrexian Altar by sacrificing Living Lightning, adding {W}.
When Living Lightning dies, it and Graceful Reprieve trigger.
Resolve the Living Lightning trigger, returning Graceful Reprieve from your graveyard to your hand.
Resolve the Graceful Reprieve trigger, returning Living Lightning from your graveyard to the battlefield.
Repeat.

Living Lightning

Pearl Medallion

Combos with "Graceful Reprieve"