Activate Phyrexian Altar by sacrificing the additional creature, adding one mana of any color.
Cast the creature from your graveyard by paying its mana cost. It will not enter with a finality counter on it due to Solemnity.
Repeat.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite storm count

Leonardo, Sewer Samurai

Solemnity

Phyrexian Altar

Activate Ashnod's Altar by sacrificing Ornithopter.
Cast Ornithopter from your graveyard by paying {0}. It will not enter with a finality counter on it due to Solemnity.
Repeat.

Infinite colorless mana

Ashnod's Altar

Ornithopter

Activate Grinding Station by tapping it and sacrificing Ornithopter.
Cast Ornithopter from your graveyard by paying {0}. It will not enter with a finality counter on it due to Solemnity.
When Ornithopter enters, Grinding Station triggers, untapping Grinding Station.
Repeat.

Infinite mill

Infinite self-mill

Grinding Station

Combos with "Leonardo, Sewer Samurai"