Undercellar Myconid, Enduring Renewal, and Phyrexian Altar

Prerequisites

• Undercellar Myconid on the battlefield
• Enduring Renewal on the battlefield
• Phyrexian Altar on the battlefield
• available

Steps

1. Activate Phyrexian Altar by sacrificing Undercellar Myconid, adding
2. Undercellar Myconid dies, triggering itself and Enduring Renewal
3. Resolve the Undercellar Myconid trigger, creating a 1/1 Saproling creature token
4. Resolve the Enduring Renewal trigger, returning Undercellar Myconid from your graveyard to your hand
5. Activate Phyrexian Altar by sacrificing the Saproling token, adding
6. Cast Undercellar Myconid by paying
7. Undercellar Myconid enters the battlefield, creating a 1/1 Saproling creature token
8. Activate Phyrexian Altar by sacrificing the Saproling token, adding
9. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers
• Infinite storm count