Cast any instant or sorcery by paying its mana cost.
Holding priority, activate Pyromancer's Goggles by tapping it, adding {R}.
Cast Flare of Duplication by paying its mana cost or by sacrificing a nontoken red creature, targeting the instant or sorcery cast in step 1.
Pyromancer's Goggles triggers, copying Flare of Duplication, with the copy targeting the original Flare of Duplication.
Resolve the copy of Flare of Duplication, creating a copy of Flare of Duplication targeting the original Flare of Duplication.
Repeat step 5.

Infinite magecraft triggers

Pyromancer's Goggles

Flare of Duplication

Cast the additional sorcery by paying its mana cost.
Alania triggers; choose not to have an opponent draw a card.
Holding priority, cast Flare of Duplication by paying {1}{R}{R}, targeting the additional sorcery.
Alania triggers, causing an opponent to draw a card and you to copy Flare of Duplication, with the copy targeting the original Flare of Duplication.
Resolve the copy of Flare of Duplication, copying the original Flare of Duplication, with the copy targeting the original Flare of Duplication.
Repeat step 5.

Alania, Divergent Storm

Cast the additional instant or sorcery by paying its mana cost.
If Adaptive Training Post had two charge counters on it, it triggers, putting a charge counter on it.
Holding priority, activate Adaptive Training Post by removing three charge counters from it, copying the next instant or sorcery spell you cast this turn.
Cast Flare of Duplication by paying its mana cost, targeting the spell cast in step 1.
Adaptive Training Post triggers, copying Flare of Duplication, with the copy targeting the original Flare of Duplication.
Resolve the copy of Flare of Duplication, copying the original Flare of Duplication, with the copy targeting the original Flare of Duplication.
Repeat step 5.

Adaptive Training Post

Cast Twinflame by paying {3}{R}{R}, targeting any two creatures.
Holding priority, cast Flare of Duplication by paying its mana cost, copying Twinflame, with the copy targeting Priest of Urabrask and Pinnacle Monk
Resolve the copy of Twinflame, creating a token copy of Priest of Urabrask and Pinnacle Monk with haste.
When the Priest of Urabrask and Pinnacle Monk tokens enter, they trigger.
Resolve the Priest of Urabrask trigger, adding {R}{R}{R}.
Resolve the Pinnacle Monk trigger, returning Flare of Duplication from your graveyard to your hand.
Repeat from step 2.

Infinite LTB

Infinite ETB

Infinite storm count

Infinite red mana

Infinite creature tokens with haste

Twinflame

Priest of Urabrask

Pinnacle Monk // Mystic Peak

Cast Chandra's Ignition by paying {3}{R}{R}.
Holding priority, cast Flare of Duplication by paying {1}{R}{R}.
Kalamax's first and second abilities trigger.
Resolve the first ability, creating a copy of Flare of Duplication targeting Chanrda's Ignition.
Resolve the second ability, putting a +1/+1 counter on Kalamax.
Resolve the Flare of Duplication copy, creating a copy of Flare of Duplication.
Kalamax's second ability triggers, putting a +1/+1 counter on itself.
Repeat from step 6 any number of times.
Once you have an arbitrarily large Kalamax, resolve Chandra's Ignition, causing Kalamax to deal damage equal to its power to each other creature and each opponent.

Infinite damage

Infinite +1/+1 counters on Kalamax

Kalamax, the Stormsire

Chandra's Ignition

Cast Arcbond by paying {2}{R}, targeting Bloodthirsty Conqueror.
Holding priority, cast Flare of Duplication by paying its mana cost or by sacrificing a nontoken red creature, copying Arcbond, with the copy targeting another indestructible creature you control.
Resolve both Arcbonds.
Deal damage to Bloodthirsty Conqueror.
Arbond triggers, dealing that much damage to each player and each other creature.
Bloodthirsty Conqueror triggers for each opponent dealt damage, and Arcbond triggers due to the other indestructible creature being dealt damage.
Resolve all Bloodthirsty Conqueror triggers, causing you to gain life.
Resolve the Arcbond trigger, dealing that much damage to each player and each other creature.
Bloodthirsty Conqueror triggers for each opponent dealt damage, and Arcbond triggers due to Bloodthirsty Conqueror being dealt damage.
Resolve all Bloodthirsty Conqueror triggers, causing you to gain life.
Resolve the Arcbond trigger, dealing that much damage to each player and each other creature.
Repeat form step 6.

Infinite lifegain triggers

Infinite lifegain

Bloodthirsty Conqueror

Arcbond

Cast Reality Spasm by paying at least {3}{U}{U}, targeting at least three permanents and choosing the untap mode.
Holding priority, cast Flare of Duplication by paying its mana cost or by sacrificing a red nontoken creature, copying Reality Spasm, targeting at least three permanents.
Holding priority, activate at least two mana-producing permanents you control by tapping them, adding at least {1}{U}.
Activate Errant by paying {1}{U} and tapping it, copying the Reality Spasm copy, targeting Errant and at least two mana-producing permanents you control.
Resolve the copy of Reality Spasm from step 3, untapping Errant and at least two mana-producing permanents you control.
Repeat from step 3.

Combos with "Flare of Duplication"