Cast Unexpected Windfall by paying {R}{R} and discarding a card from your hand.
If you have less than four experience counters, Mizzix triggers, causing you to get an experience counter.
Holding priority, cast Retierate with buyback by paying {R}{R}, creating a copy of Unexpected Windfall and returning Reiterate to your hand.
Resolve the copy of Unexpected Windfall, causing you to draw two cards and create two Treasure tokens.
Activate both Treasure tokens by tapping and sacrificing them, adding {R}{R}.
Repeat from step 3.

Infinite card draw

Infinite draw triggers

Near-infinite magecraft triggers

Near-infinite storm count

Mizzix of the Izmagnus

Unexpected Windfall

Reiterate

Cast Unexpected Windfall by paying {2}{R}{R} and discarding a card.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Activate the Treasure by tapping and sacrificing it, adding {U}{U} or {R}{R}.
Activate Nivix Guildmage's second ability by paying {2}{U}{R}, copying Unexpected Windfall.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Resolve the copy of Unexpected Windfall, creating two Treasure artifact tokens and causing you to draw two cards.
Activate two Treasures by tapping and sacrificing them, adding {U}{U}{R}{R}.
Repeat from step 4.

Near-infinite colored mana

Near-infinite power for a creature

Near-infinite Treasure tokens

Nivix Guildmage

Storm-Kiln Artist

Goldspan Dragon

Cast Unexpected Windfall by paying {2}{R}{R} and discarding a card.
Storm-Kiln Artist triggers, creating two Treasure artifact tokens.
Activate the Treasures by tapping and sacrificing them, adding {U}{R}.
Activate Nivix Guildmage's second ability by paying {2}{U}{R}, copying Unexpected Windfall.
Storm-Kiln Artist triggers, creating two Treasure artifact tokens.
Resolve the copy of Unexpected Windfall, creating three Treasure artifact tokens and causing you to draw two cards.
Activate four Treasures by tapping and sacrificing them, adding {2}{U}{R}.
Repeat from step 4.

Xorn

Cast Unexpected Windfall by paying {2}{R}{R} and discarding a card.
Holding priority, activate Nivix Guildmage's second ability by paying {U}{R}, copying Unexpected Windfall.
Resolve the copy of Unexpected Windfall, creating two Treasure artifact tokens and causing you to draw two cards.
Activate both Treasures by tapping and sacrificing them, adding {U}{R}.
Repeat from step 2.

Training Grounds

Activate Sunforger by paying {R}{W} and unattaching it, searching your library for Jeska's Will and casting it without paying its mana cost, adding at least six {R}.
Activate Sunforger's equip ability by paying {1}, attaching it to Zirda.
Activate Sunforger by paying {R}{W} and unattaching it, searching your library for Unexpected Windfall and casting it without paying its mana cost and discarding a card.
Resolve Unexpected Windfall, causing you to draw two cards and create two Treasures.
Activate Sunforger's equip ability by paying {1}, attaching it to Zirda.
Activate Tomb Trawler twice by paying {2}, putting Unexpected Windfall and Jeska's Will from your graveyard onto the bottom of your library.
Activate two Treasures by tapping and sacrificing them, adding {W}{W}.
Repeat.

Combos with "Unexpected Windfall"