Felidar Guardian, Altar of the Brood, and Phyrexian Metamorph

Prerequisites

• Felidar Guardian on the battlefield
• Altar of the Brood on the battlefield
• Phyrexian Metamorph in hand
• available

Steps

1. Cast Phyrexian Metamorph by paying
2. Phyrexian Metamorph enters the battlefield as a copy of Felidar Guardian, triggering Altar of the Brood and itself
3. Resolve the Altar of the Brood trigger, causing each opponent to mill a card
4. Resolve the Phyrexian Metamorph's trigger, blinking Felidar Guardian
5. Felidar Guardian enters the battlefield, triggering Altar of the Brood and itself
6. Resolve the Altar of the Brood trigger, causing each opponent to mill a card
7. Resolve the Felidar Guardian's trigger, blinking Phyrexian Metamorph
8. Repeat from step 2

Results

• Infinite ETB
• Infinite LTB
• Infinite mill