There are four or more permanent cards in your graveyard.
.
Notable Prerequisites
You have enough mana available each turn to cast the extra turn spell and enough mana each extra turn to cast
Coati Scavenger.
You have not cast a spell using
Kotis.
Steps
Cast the extra turn spell by paying its mana cost, causing you to take an extra turn after this one.
Move to your extra turn.
Activate
Altar of Dementia by sacrificing
Coati Scavenger, causing you to mill cards equal to
Coati Scavenger's power.
Cast
Coati Scavenger from your graveyard by paying its mana cost and exiling three other cards from your graveyard, ensuring not to exile the extra turn spell.
When
Coati Scavenger enters the battlefield, it triggers, returning the extra turn spell from your graveyard to your hand.