Doom's Time Platform, Shivan Sand-Mage, Time Walk, and Elrond, Moon-Reader

Prerequisites

• Doom's Time Platform on the battlefield
• Shivan Sand-Mage on the battlefield
• Time Walk in the graveyard
• Elrond, Moon-Reader on the battlefield
• each turn available

Steps

1. Declare any creature as an attacker
2. When you do, Doom's Time Platform triggers, exiling Time Walk from your graveyard with two time counters on it
3. Blink Shivan Sand-Mage using Elrond
4. When Shivan Sand-Mage enters, it triggers, removing two time counters from Time Walk
5. Time Walk's suspend ability triggers, causing you to cast it without paying its mana cost
6. Resolve Time Walk, causing you to take an extra turn after this one
7. Repeat each turn

Results

• Infinite turns
• Lock