Chthonian Nightmare + Capture of Jingzhou + Timeless Witness

Chthonian Nightmare

Capture of Jingzhou

Timeless Witness

How it works

1. Cast Capture of Jingzhou by paying 3, causing you to take an extra turn after this one.
2. Move to your next turn.
3. Cast Chthonian Nightmare by paying 1.
4. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get EEE.
5. Activate Chthonian Nightmare by paying EEEE, sacrificing a creature with mana value 2 or less, and returning Chthonian Nightmare from the battlefield to your hand, returning Timeless Witness from your graveyard to the battlefield.
6. When Timeless Witness enters the battlefield, it triggers, returning Capture of Jingzhou from your graveyard to your hand.
7. Cast Chthonian Nightmare by paying 1.
8. When Chthonian Nightmare enters the battlefield, it triggers, causing you to get EEE.
9. Activate Chthonian Nightmare by paying at most EE, sacrificing Timeless Witness, and returning Chthonian Nightmare from the battlefield to your hand, returning a creature with mana value 2 or less from your graveyard to the battlefield.
10. Repeat.

This loop achieves an infinite turn lock by recycling key pieces using the energy generated by Chthonian Nightmare upon entering the battlefield. You use that energy, along with sacrificing a small creature, to return Timeless Witness from your graveyard, which in turn triggers its ability to pull the sorcery Capture of Jingzhou right back to your hand for another cast. By continually re-casting and bouncing Chthonian Nightmare alongside Timeless Witness, you endlessly repeat this cycle to chain extra turns indefinitely until victory is secured.