Kotis, Sibsig Champion + Altar of Dementia + Greenwarden of Murasa

Kotis, Sibsig Champion

Altar of Dementia

Greenwarden of Murasa

How it works

1. Cast the extra turn spell by paying its mana cost, causing you to take an extra turn after this one.
2. Move to your extra turn.
3. Activate Altar of Dementia by sacrificing Greenwarden of Murasa, causing you to mill cards equal to Greenwarden of Murasa's power.
4. Cast Greenwarden of Murasa from your graveyard by paying its mana cost and exiling three other cards from your graveyard, ensuring not to exile the extra turn spell.
5. When Greenwarden of Murasa enters the battlefield, it triggers, returning the extra turn spell from your graveyard to your hand.
6. Repeat.