Cast any instant or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Reverberate by paying {R}{R}, targeting that spell.
Cast Twincast by paying {U}{U}, copying Reverberate, with the copy targeting Reverberate.
Resolve the copy of Reverberate, copying the original Reverberate, with the copy targeting the original Reverberate.
Repeat step 4.

Infinite magecraft triggers

Twincast

Reverberate

Cast any instant or sorcery spell by paying its mana cost.
Holding priority, cast Increasing Vengeance by paying {R}{R}, targeting that spell.
Cast Twincast by paying {U}{U}, copying Increasing Vengeance, with the copy targeting Increasing Vengeance.
Resolve the copy of Increasing Vengeance, copying the original Increasing Vengeance, with the copy targeting the original Increasing Vengeance.
Repeat step 4.

Increasing Vengeance

Cast any other instant and/or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Expansion by paying {U/R}{U/R}, copying the next instant or sorcery spell you cast with mana value four or less.
Cast Twincast by paying {U}{U}, targeting the instant or sorcery spell cast in step 1.
The delayed trigger from Expansion triggers, copying Twincast, with the copy targeting the original Twincast.
Resolve the copy of Twincast, copying Twincast, with the copy targeting the original Twincast.
Repeat step 5.

Expansion // Explosion

Cast Chandra's Ignition by paying {3}{R}{R}.
Holding priority, cast Twincast by paying {U}{U}, creating a copy of Chandra's Ignition.
Kalamax first and second abilities triggers.
Resolve the first ability, creating a copy of Twincast.
Resolve the second ability, putting a +1/+1 counter on itself.
Resolve the Twincast copy, creating a copy of Twincast.
Repeat from step 3.
Once you have infinite copies of Twincast and arbitrarily large Kalamax, you may resolve Chandra's Ignition, dealing infinite damage to each other creature and each opponent.

Infinite damage

Infinitely large Kalamax

Kalamax, the Stormsire

Chandra's Ignition

Cast any instant or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Fork by paying {R}{R}, targeting that spell.
Cast Twincast by paying {U}{U}, copying Fork, with the copy targeting Fork.
Resolve the copy of Fork, copying the original Fork, with the copy targeting the original Fork.
Repeat step 4.

Fork

Cast the additional sorcery by paying its mana cost.
Alania triggers; choose not to have an opponent draw a card.
Holding priority, cast Twincast by paying [cost], targeting the additional sorcery.
Alania triggers, causing an opponent to draw a card and you to copy Twincast, with the copy targeting the original Twincast.
Resolve the copy of Twincast, copying the original Twincast, with the copy targeting the original Twincast.
Repeat step 5.

Alania, Divergent Storm

Cast any other instant and/or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Dual Strike by paying {R}{R}, copying the next instant or sorcery spell you cast with mana value four or less.
Cast Twincast by paying {U}{U}, targeting the instant or sorcery spell cast in step 1.
Dual Strike triggers, copying Twincast, with the copy targeting the original Twincast.
Resolve the copy of Twincast, copying Twincast, with the copy targeting the original Twincast.
Repeat step 5.

Dual Strike

Cast an instant or sorcery spell, or wait for an opponent to cast one.
Holding priority, cast Twincast by paying {U}{U}, targeting the spell.
Activate Rootha by paying {2} and returning it to your hand, copying Twincast, with the copy targeting the original Twincast.
Resolve the copy of Twincast, copying Twincast, targeting the original Twincast.
Repeat step 4.

Rootha, Mercurial Artist

Cast Dualcaster Mage for {1}{R}{R}.
Holding priority, cast Double Major targeting Dualcaster Mage.
Holding priority, cast Twincast, copying Double Major, targeting Dualcaster.
Let the copied Double Major resolve, creating a token copy of Dualcaster Mage.
Dualcaster Mage enters the battlefield, copying Double Major, targeting Dualcaster Mage.
Repeat from Step 4.

Infinite creature tokens

Infinite ETB

Double Major

Dualcaster Mage

Activate all mana producing nonland permanents you control by tapping them, adding at least {2}{U}.
Cast Dramatic Reversal by paying {1}{U}.
Holding priority, cast Twincast by paying {U}{U}, creating a copy of Dramatic Reversal.
Activate Errant by paying {1}{U} and tapping it, creating a copy of the Dramatic Reversal copy.
Resolve the first Dramatic Reversal copy, untapping all nonland permanents you control.
Activate all mana producing nonland permanents you control by tapping them, adding at least {2}{U}.
Repeat from step 4.

Infinite mana nonland permanents you control can produce

Infinite untap of nonland permanents you control

Errant, Street Artist

Dramatic Reversal

Cast Bond of Insight by paying {3}{U}.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Holding priority, activate the Treasure by tapping and sacrificing it, adding {U}.
Cast Twincast by paying {U}{U}, targeting Bond of Insight.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Resolve the copy of Twincast, copying Bond of Insight.
Storm-Kiln Artist triggers, creating a Treasure artifact token.
Resolve the copy of Bond of Insight, causing each player to mill four cards and return Twincast and any other instant or sorcery from your graveyard to your hand.
Activate the Treasures by tapping and sacrificing them, adding {U}{U}.
Repeat from step 4.

Infinite mill

Infinite self-mill

Infinite storm count

Put all instant and sorcery cards from your graveyard and library into your hand

Storm-Kiln Artist

Bond of Insight

Cast Bond of Insight by paying {3}{U}.
Holding priority, cast Turnabout by paying {2}{U}{U}, untapping all lands you control.
Activate all mana-producing lands you control by tapping them, adding at least {2}{U}{U}{U}{U}.
Holding priority, cast Twincast by paying {U}{U}, copying Bond of Insight.
Resolve the copy of Bond of Insight, causing each player to mill four cards, and returning Turnabout and Twincast from your graveyard to your hand.
Repeat from step 2.
If lands you control can tap to produce at least {3}{U}{U}{U}{U}, this combo nets infinite mana, which can be used to infinitely cast instants instead of continuing to copy Turnabout.

Infinite mana lands you control can produce

Infinite casts of instants in your graveyard and/or hand

Turnabout

Cast Turnabout for {2}{U}{U}.
In response, Cast Twincast targeting Turnabout for {U}{U}.
In response, Activate Izzet Guildmage's ability for {2}{U} targeting Twincast.
Resolve the Izzet Guildmage's activated ability to copy Twincast targeting Turnabout with the copy of Twincast.
Resolve the copy of Turnabout, created by the copy of Twincast to untap your lands that can produce at least {3}{U}.
Repeat.

Infinite colored mana

Infinite colorless mana

Izzet Guildmage

Cast Pair o' Dice Lost by paying {3}{G}{G}.
Storm-Kiln Artist triggers, creating a Treasure token.
Holding priority, activate the Treasure by tapping and sacrificing it, adding {U}.
Cast Twincast by paying {U}{U}, targeting Pair o' Dice Lost.
Storm-Kiln Artist triggers, creating a Treasure token.
Resolve the copy of Twincast, copying Pair o' Dice Lost.
Storm-Kiln Artist triggers, creating a Treasure token.
Resolve the copy of Pair o' Dice Lost, causing you to roll two d6 and return Twincast and any other applicable card(s) to your hand from your graveyard.
Activate the Treasures by tapping and sacrificing them, adding {U}{U}.
Repeat from step 4.

Combos with "Twincast"