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

The Sixth Doctor

Karn's Temporal Sundering

Isochron Scepter

Remand

How it works

1. Cast Karn's Temporal Sundering by paying 4.
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 Remand without paying its mana cost.
5. Resolve Remand, returning the original Karn's Temporal Sundering to your hand and causing you to draw a card.
6. Repeat each turn.

This clever loop lets you take infinite turns by perpetually recycling a legendary sorcery, fueled by the repeatable interaction of Isochron Scepter and Remand. Because Karn's Temporal Sundering is a historic spell, casting it triggers The Sixth Doctor to generate an unlegendary copy that grants you an extra turn. Before the original spell can resolve and exile itself, you use Isochron Scepter to cast Remand, countering your own original Karn's Temporal Sundering and bouncing it straight back to your hand so you can cast it all over again next turn.