Cast Marketback Walker by paying {0}.
Marketback Walker enters and dies as a state-based action due to having 0 toughness.
Metastatic Evangel triggers, causing you to proliferate and put a +1/+1 counter on Evolution Witness.
Evolution Witness triggers, returning Marketback Walker from your graveyard to your hand.
Repeat.

Infinite LTB

Infinite ETB

Infinite death triggers

Infinite storm count

Infinite proliferate

Metastatic Evangel

Evolution Witness

Marketback Walker

Cast Marketback Walker by paying {1}, causing it to enter the battlefield with a +1/+1 counter on it.
Activate Together Forever by paying {1}, targeting Marketback Walker.
Activate Ashnod's Altar by sacrificing Marketback Walker, adding {C}{C}.
When Marketback Walker dies, it and Together Forever trigger.
Resolve the Marketback Walker trigger, causing you to draw a card.
Resolve the Together Forever trigger, returning Marketback Walker from your graveyard to your hand.
Repeat.

Infinite card draw

Near-infinite ETB

Infinite draw triggers

Near-infinite storm count

Near-infinite LTB

Near-infinite death triggers

Near-infinite sacrifice triggers

Together Forever

Ashnod's Altar

Foundry Inspector

Cast Marketback Walker by paying {0}.
Marketback Walker enters and dies as a state-based action due to having 0 toughness, triggering Mortuary and Grim Haruspex.
Resolve the Mortuary trigger, putting Marketback Walker from your graveyard onto the top of your library.
Resolve the Grim Haruspex trigger, causing you to draw a card, thus drawing Marketback Walker from your library.
Repeat.

Mortuary

Grim Haruspex

Cast Marketback Walker by paying {0}.
Marketback Walker enters the battlefield and dies as a state-based action due to having 0 toughness.
Enduring Renewal triggers, returning Marketback Walker from your graveyard to your hand.
Repeat.

Enduring Renewal

Cast Marketback Walker either from your hand by paying {0} or from the top of your library by paying 0 life.
Marketback Walker enters and dies as a state-based action due to having 0 toughness.
Mortuary triggers, putting Marketback Walker from your graveyard onto the top of your library.
Repeat.

Bolas's Citadel

Activate Emry by tapping it, allowing you to cast Marketback Walker from your graveyard this turn.
Cast Marketback Walker from your graveyard by paying {0}.
Marketback Walker enters the battlefield and dies as a state-based action due to having 0 toughness.
Emry triggers, untapping itself.
Repeat.

Emry, Lurker of the Loch

Thornbite Staff

Cast Marketback Walker by paying {0}.
Marketback Walker enters the battlefield and dies as a state-based action due to having 0 toughness.
Luminous Broodmoth triggers, returning Marketback Walker from your graveyard to the battlefield without a flying counter due to Solemnity.
Repeat from step 2.

Combos with "Marketback Walker"