Mortuary + Fecundity + Marketback Walker

Mortuary

Fecundity

Marketback Walker

How it works

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

This brilliant loop lets you continuously cycle Marketback Walker through your graveyard and back into your hand by paying zero mana to cast it. As soon as it enters with zero toughness and hits the graveyard, Mortuary ensures the automaton immediately returns to the top of your library instead of staying put, while Fecundity rewards that death by letting you draw it right back into your hand.