Kenrith, the Returned King, Eternal Witness, Temporal Manipulation, and Ashnod's Altar

Prerequisites

• Kenrith, the Returned King on the battlefield
• Eternal Witness on the battlefield
• Temporal Manipulation in the graveyard
• Ashnod's Altar on the battlefield
• each turn available

Steps

1. Activate Ashnod's Altar by sacrificing Eternal Witness, adding
2. Activate Kenrith's last ability by paying , returning Eternal Witness from your graveyard to the battlefield
3. Eternal Witness enters the battlefield, returning Temporal Manipulation from your graveyard to your hand
4. Cast Temporal Manipulation by paying , causing you to take an extra turn after this one
5. Repeat

Results

• Infinite turns