Kenrith, the Returned King + Archaeomancer + Time Warp + Ashnod's Altar

Kenrith, the Returned King

Archaeomancer

Time Warp

Ashnod's Altar

How it works

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