Maestros Charm | Underworld Breach | Storm-Kiln Artist

(and two other cards)

Maestros Charm in hand or in your graveyard.
Thassa's Oracle in hand or in your graveyard or in your library.
All other permanents on the battlefield.
You have cast at least one instant or sorcery this turn.
You have at least three other cards in your graveyard if
Maestros Charm is in your graveyard.
({U} magic symbol) ({B} magic symbol) ({R} magic symbol) available.

At the beginning of your combat phase,
Rionya triggers, creating at least two token copies of
Storm-Kiln Artist.
Move to your post-combat main phase.
If
Maestros Charm is in your hand, cast it by paying ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) .
Otherwise, cast it from your graveyard for its escape cost by paying ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) and exiling three cards from your graveyard, ensuring not to exile
Thassa's Oracle if it is in your graveyard.
Each
Storm-Kiln Artist triggers, creating at least three Treasure tokens.
Resolve
Maestros Charm, causing you to look at the top five cards of your library, put one of them in your hand and put the rest into your graveyard.
If you don't have an empty library, activate three Treasure tokens by tapping and sacrificing them, adding ({U} magic symbol) ({B} magic symbol) ({R} magic symbol) .
Repeat from step 3 until you have an empty library.
Activate two Treasure tokens by tapping and sacrificing them, adding ({U} magic symbol) ({U} magic symbol) .
If
Thassa's Oracle is in your hand, cast it by paying ({U} magic symbol) ({U} magic symbol) .
Otherwise, cast it for its escape cost by paying ({U} magic symbol) ({U} magic symbol) and exiling three cards from your graveyard.
Thassa's Oracle enters the battlefield, causing you to win the game.