Activate Urza by paying {6}, creating a copy of Simulacrum Synthesizer that is a 1/1 Construct.
When the Simulacrum Synthesizer token enters the battlefield, its first ability and each other SImulacrum Synthesizer you control's second abilities trigger.
Resolve the first trigger, causing you to scry 2.
Resolve the remaining triggers, creating a 0/0 Construct artifact creature token for each trigger resolved this way.
Activate Krark-Clan Ironworks by sacrificing a 0/0 Construct, adding {C}{C}.
Repeat step 5 for each other 0/0 Construct you control, if applicable.
Repeat from step 1.

Infinite LTB

Infinite ETB

Infinite sacrifice triggers

Infinite death triggers

Infinite colorless mana

Infinite creature tokens

Infinite scry

Infinite creature copies of artifacts you control

Urza, Prince of Kroog

Simulacrum Synthesizer

Krark-Clan Ironworks

Activate Chrome Dome by paying {5}, creating a token copy of Simulacrum Synthesizer.
When the Simulacrum Synthesizer token enters, its first ability and the nontoken Simulacrum Synthesizer's second ability trigger.
Resolve the token's trigger, causing you to scry 2.
Resolve the nontoken Simulacrum Synthesizer's trigger, creating a 0/0 Construct artifact creature token.
Activate Krark-Clan Ironworks by sacrificing the Construct, adding {C}{C}.
Activate Chrome Dome by paying {5}, creating a token copy of Simulacrum Synthesizer.
When the Simulacrum Synthesizer token enters, its first ability and each other Simulacrum Synthesizer's second ability trigger.
Resolve the first trigger, causing you to scry 2.
Resolve each other trigger, creating that many 0/0 Construct artifact creature tokens.
Activate Krark-Clan Ironworks three times by sacrificing a Simulacrum Synthesizer token and two Constructs, adding six {C}.
Repeat from step 6.

Infinite copies of artifacts you control with haste

Infinite creature tokens with haste

Infinite scry 2

Chrome Dome

Cast Moritte of the Frost from your hand or from the command zone by paying {2}{G}{U}{U} plus commander tax, if applicable, choosing to have it enter the battlefield as a copy of Staff of Eden.
Put Moritte of the Frost into your graveyard due to the legend rule.
Morrite of the Frost's enters-the-battlefield ability and Simulacrum Synthesizer's second ability trigger.
Resolve the Simulacrum Synthesizer trigger, creating a 0/0 Construct artifact creature token.
Resolve the Moritte of the Frost trigger, returning Moritte of the Frost from your graveyard to the battlefield as a copy of Staff of Eden.
Repeat from step 2.

Infinite power and toughness for certain creatures

Moritte of the Frost

Staff of Eden, Vault's Key

Cast the Vehicle by paying its mana cost.
When the Vehicle enters the battlefield, Simulacrum Synthesizer triggers, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control.
Activate the Vehicle's crew ability by tapping the Construct, causing the Vehicle to become an artifact creature until end of turn.
Activate Ashnod's Altar by sacrificing the Vehicle.
When the Vehicle dies, Valkyrie's Call triggers, returning the Vehicle from your graveyard to the battlefield. It will not be an Angel because the Vehicle is no longer a creature and cannot gain creature types.
When the Vehicle enters the battlefield, Simulacrum Synthesizer triggers, creating a 0/0 Construct artifact creature token that gets +1/+1 for each artifact you control.
Repeat from step 3.

Infinite tapped creature tokens

Vehicle with MV >= 3 and a Crew Ability

Valkyrie's Call

Ashnod's Altar

Cast Mycosynth Lattice by paying {6}.
When Mycosynth Lattice enters the battlefield, Simulacrum Synthesizer's second ability triggers, creating a 0/0 Contruct artifact creature token that enters the battlefield as a copy of Essence of the Wild.
When the Essence of the Wild token enters the battlefield as an artifact due to Mycosynth Lattice, Simulacrum Synthesizer's second ability triggers, creating a 0/0 Contruct artifact creature token that enters the battlefield as a copy of Essence of the Wild.
Repeat step 3.

Draw the game

Essence of the Wild

Mycosynth Lattice

Combos with "Simulacrum Synthesizer"