At the beginning of your upkeep, Court of Vantress' second ability triggers, either causing it to become a copy of Widespread Thieving until end of turn if you aren't the monarch, or creating a token copy of Widespread Thieving if you are the monarch.
Cast Heaven Sent by paying ({U} magic symbol) ({R} magic symbol) .
Widespread Thieving and either Court of Vantress or the Widespread Thieving token trigger, creating two Treasure artifact tokens.
Activate the Treasures by tapping and sacrificing them, adding ({U} magic symbol) ({R} magic symbol) .
Resolve Heaven Sent, choosing to have it enter the battlefield with three chapter counters on it due to its read ahead ability.
Heaven Sent's third chapter ability triggers, dealing 1 damage to each opponent, and causing you to draw seven cards if an opponent has 0 or less life, or otherwise exile Heaven Sent with the ability to play it this turn.
If Heaven Sent was exiled this way, repeat from step 2 until Heaven Sent is not exiled.