Spark Double, and Felidar Guardian

Prerequisites

• Spark Double in hand
• Felidar Guardian on the battlefield

Steps

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

Results

• Infinite LTB
• Infinite ETB