Isochron Scepter + Karn's Temporal Sundering + The Sixth Doctor + Unsubstantiate

Mana needed: {6}{U}{U} each turn

GU identity

Commander legal

The 4 combo pieces

• Isochron Scepter
• Karn's Temporal Sundering
• The Sixth Doctor
• Unsubstantiate

How to execute it

1. Cast Karn's Temporal Sundering by paying {4}{U}{U}.
2. The Sixth Doctor triggers, copying Karn's Temporal Sundering.
3. Resolve the copy of Karn's Temporal Sundering, causing you to take an extra turn after this one.
4. Holding priority, activate Isochron Scepter by paying {2} and tapping it, casting a copy of Unsubstantiate without paying its mana cost.
5. Resolve Unsubstantiate, returning the original Karn's Temporal Sundering to your hand.
6. Repeat each turn.

What the combo produces

• Infinite turns
• Lock