Dack's Duplicate, and Wispweaver Angel

Prerequisites

• Dack's Duplicate in hand
• Wispweaver Angel on the battlefield

Steps

1. Cast Dack's Duplicate by paying its mana cost, choosing to have it enter the battlefield as a copy of Wispweaver Angel When Dack's Duplicate enters the battlefield, it triggers, blinking Wispweaver Angel
2. When Wispweaver Angel enters the battlefield, it triggers, blinking Dack's Duplicate
3. Choose to have Dack's Duplicate enter the battlefield as a copy of Wispweaver Angel
4. Repeat from step 2

Results

• Infinite ETB
• Infinite LTB