Activate Krark-Clan Ironworks by sacrificing Sword of the Meek, adding {C}{C}.
Sword of the Meek dies, triggering Slagstone Refinery, creating a tapped Powerstone token that enters the battlefield as a 1/1 creature due to March of the Machines and Master of Etherium.
Sword of the Meek triggers, returning itself from your graveyard to the battlefield, but not attaching itself to the Powerstone due to Sword of the Meek becoming a creature.
Repeat.

Infinite colorless mana

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

Infinite tapped creature tokens

Infinite tapped Powerstone tokens

Slagstone Refinery

March of the Machines

Sword of the Meek

Krark-Clan Ironworks

Master of Etherium

Activate Ashnod's Altar by sacrificing Sword of the Meek, adding {C}{C}.
Sword of the Meek dies, triggering Slagstone Refinery, creating a tapped Powerstone token that enters the battlefield as a 1/1 creature due to March of the Machines and Master of Etherium.
Sword of the Meek triggers, returning itself from your graveyard to the battlefield, but not attaching itself to the Powerstone due to Sword of the Meek becoming a creature.
Repeat.

Ashnod's Altar

Combos with "Master of Etherium"