Activate Ashnod's Altar by sacrificing another nontoken artifact creature, adding {C}{C}.
When the artifact creature dies, Nim Deathmantle triggers, causing you to pay {4} to return the artifact creature from your graveyard to the battlefield, and attach Nim Deathmantle to it.
When the artifact creature enters the battlefield, The Prydwen triggers, creating a 2/2 Human Knight creature token.
Activate Ashnod's Altar by sacrificing the Human Knight, adding {C}{C}.
Repeat.

Infinite death triggers

Infinite ETB

Infinite LTB

Infinite sacrifice triggers

The Prydwen, Steel Flagship

Nim Deathmantle

Ashnod's Altar

Activate Boommobile's crew ability by tapping Emiel, causing Boommobile to become an artifact creature until end of turn.
Activate Emiel by paying {3}, blinking Boommobile.
When Boommobile enters the battlefield, it and The Prydwen trigger.
Resolve the Prydwen trigger, creating a 2/2 Human Knight creature token.
Resolve the Boommobile trigger, adding four mana of any color that can only be spent to activate abilities.
Activate Boommobile's crew ability by tapping the Human Knight, causing Boommobile to become an artifact creature until end of turn.
Repeat from step 2.

Infinite damage

Infinite tapped creature tokens

Infinite colored mana that can only be spent to activate abilities

Boommobile

Emiel the Blessed

Cast Sword of the Meek by paying {2}.
When Sword of the Meek enters the battlefield, The Prydwen triggers.
Holding priority, activate Krark-Clan Ironworks by sacrificing Sword of the Meek.
Resolve the Prydwen trigger, creating a 2/2 Human Knight and a 1/1 Frog creature token.
When the Frog enters the battlefield, Sword of the Meek triggers, returning Sword of the Meek from your graveyard to the battlefield attached to the Soldier.
Repeat from step 2.

Combos with "The Prydwen, Steel Flagship"