Descent into Avernus has at least four descent counters on it.
({1} magic symbol) each turn available.
Steps
At the beginning of your upkeep, Descent into Avernus triggers.
Holding priority, activate Circle of Protection: Red by paying ({1} magic symbol) , preventing the next amount of damage Descent into Avernus would deal you this turn.
Resolve the Descent into Avernus trigger, putting two descent counters on it, then causing each player to create a number of Treasure tokens equal to the number of descent counters on Descent into Avernus, and causing each opponent to be dealt an amount of damage equal to the number of descent counters on Descent into Avernus.
Activate Time Sieve by tapping it and sacrificing five Treasures, causing you to take an extra turn after this one.