Colfenor, the Last Yew, Hangarback Walker, and Ashnod's Altar

Prerequisites

• Colfenor, the Last Yew on the battlefield
• Hangarback Walker on the battlefield
• Ashnod's Altar on the battlefield
• Hangarback Walker has at least one +1/+1 counter on it

Steps

1. Sacrifice Hangarback Walker to Ashnod's Altar, adding
2. Hangarback Walker and Colfenor trigger
3. Resolve the Hangarback Walker trigger, creating a Thopter token
4. Resolve the Colfenor trigger with no targets
5. Sacrifice the Thopter token to Ashnod's Altar, adding
6. Colfenor triggers, returning Hangarback Walker from your graveyard to your hand
7. Cast Hangarback Walker for X=1
8. Repeat

Results

• Infinite colorless mana
• Infinite creature tokens with flying
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite storm count
• Return any number of creatures from your graveyard to your hand