Phantom Steed, Time Stretch, and Eternal Witness

Prerequisites

• Phantom Steed on the battlefield
• Time Stretch in hand
• Eternal Witness in exile
• An opponent can not block Phantom Steed
• available

Steps

1. Cast Time Stretch, taking an extra two turns after this one
2. Attack with Phantom Steed
3. Phantom Steed triggers, creating a token copy of Eternal Witness that is tapped and attacking
4. Eternal Witness enters, returning Time Stretch from your graveyard to your hand
5. Pass the turn
6. Repeat

Results

• Infinite turns