Doom's Time Platform + Time Stretch

Prerequisites

• You control a creature that can attack and that cannot be blocked or killed by an opponent.

Steps

1. 1Cast Time Stretch by paying its mana cost, causing you to take two extra turns after this one.
2. 2Declare any creature as an attacker. When you do, Doom's Time Platform triggers, exiling Time Stretch from your graveyard with two time counters on it.
3. 3Move to your first extra turn.
4. 4At the beginning of your upkeep, Time Stretch's suspend ability triggers, removing a time counter from it.
5. 5Move to your second extra turn and repeat step 4 once.
6. 6Time Stretch's suspend ability triggers, causing you to cast it without paying its mana cost.
7. 7Resolve Time Stretch, causing you to take two extra turns after this one.
8. 8Repeat from step 2.

Effects

• Infinite turns
• Lock