Mirror Image, and Felidar Guardian

Prerequisites

• Mirror Image in hand
• Felidar Guardian on the battlefield

Steps

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

Results

• Infinite ETB
• Infinite LTB