Chthonian Nightmare, Eternal Witness, and Time Warp

Prerequisites

• Chthonian Nightmare in hand
• Eternal Witness in the graveyard
• Time Warp in hand
• You control a nontoken creature with mana value 3 or less
• the first turn, with each extra turn available

Steps

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

Results

• Infinite turns