Colfenor, the Last Yew, Sifter of Skulls, and Hangarback Walker

Prerequisites

• Colfenor, the Last Yew on the battlefield
• Sifter of Skulls on the battlefield
• Hangarback Walker in hand

Steps

1. Cast Hangarback Walker by paying
2. Hangarback Walker enters the battlefield and dies as a state-based action due to having zero or less toughness
3. Colfenor and Sifter of Skulls trigger
4. Resolve the Colfenor trigger, returning nothing from your graveyard to your hand
5. Resolve the Sifter of Skulls trigger, creating a 1/1 Eldrazi Spawn creature token
6. Activate the Eldrazi Spawn by sacrificing it, adding
7. The Eldrazi Spawn dies, triggering Colfenor, returning Hangarback Walker from your graveyard to your hand
8. Repeat

Results

• Infinite +1/+1 counters on Hangarback Walker
• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite storm count