Descent into Avernus has at least four descent counters on it.
Steps
At the beginning of your upkeep,
Descent into Avernus triggers, 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, causing each opponent to be dealt an amount of damage equal to the number of descent counters on
Descent into Avernus, and causing you to gain life 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.