Mortuary + Realmwalker + Phyrexian Marauder

Mortuary

Realmwalker

Phyrexian Marauder

How it works

1. Cast Phyrexian Marauder either from your hand or from the top of your library by paying 0.
2. Phyrexian Marauder enters the battlefield and dies as a state-based action due to having zero toughness.
3. Mortuary triggers, putting Phyrexian Marauder on top of your library from your graveyard.
4. Repeat.

This elegant little loop turns a fragile automaton into a perpetual motion machine by exploiting how the rules handle zero toughness. When you cast Phyrexian Marauder with an X of zero, it enters the battlefield as a creature with no toughness and immediately heads to the graveyard as a state-based action, which happily triggers Mortuary to place it right back on top of your library. From there, Realmwalker's changeling nature lets you name whatever creature type you please so you can immediately cast the Marauder off the top of your library all over again. By cycling this zero-cost artifact creature through the graveyard on an infinite loop, you rack up an unbounded storm count alongside endless creature enters-and-leaves-the-battlefield triggers.