Activate Phyrexian Altar by sacrificing Nomad Mythmaker, adding {W}.
Gift of Immortality triggers, returning Nomad Mythmaker to the battlefield.
Pay {0} to equip Lightning Greaves to Nomad Mythmaker.
Activate Nomad Mythmaker by paying {W} and tapping it, returning Gift of Immortality from your graveyard to the battlefield attached to Nomad Mythmaker.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Nomad Mythmaker

Gift of Immortality

Lightning Greaves

Phyrexian Altar

Activate Phyrexian Altar by sacrificing Nomad Mythmaker, adding {W}.
Gift of Immortality triggers, returning Nomad Mythmaker to the battlefield.
Activate Nomad Mythmaker by paying {W} and tapping it, returning Gift of Immortality onto the battlefield attached to Nomad Mythmaker.
Repeat.

Combos with "Nomad Mythmaker"