Hulking Metamorph, and Felidar Guardian

Prerequisites

• Hulking Metamorph in hand
• Felidar Guardian on the battlefield

Steps

1. Cast Hulking Metamorph by paying its mana cost, choosing to have it enter the battlefield as a copy of Felidar Guardian When Hulking Metamorph enters the battlefield, it triggers, blinking Felidar Guardian
2. When Felidar Guardian enters the battlefield, it triggers, blinking Hulking Metamorph
3. Choose to have Hulking Metamorph enter the battlefield as a copy of Felidar Guardian
4. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB