Echocasting Symposium, Eternal Witness, and Time Walk

Prerequisites

• Echocasting Symposium in exile
• Eternal Witness on the battlefield
• Time Walk in hand
• each turn available

Steps

1. Cast Time Walk by paying its mana cost, causing you to take an extra turn after this one
2. Move to your next turn
3. At the beginning of your precombat main phase, Echocasting Symposium's paradigm ability triggers, causing you to cast a copy of it from exile
4. Resolve the copy, creating a token copy of Eternal Witness When the Eternal Witness token enters, it triggers, returning Time Walk from your graveyard to your hand
5. Repeat

Results

• Infinite turns
• Lock