Cast the copy of the spell from exile by paying its mana cost.
When you cast that spell, Molten-Core Maestro, Storm-Kiln Artist, and Displacer Kitten trigger.
Resolve the Displacer Kitten trigger, blinking Campus Composer, which enters prepared.
Resolve the Molten-Core Maestro trigger, putting a +1/+1 counter on it and adding an amount of {R} equal to its power.
Resolve the Storm-Kiln Artist trigger, creating a Treasure token.
Activate the Treasure token by tapping and sacrificing it, adding the one non-red mana you need to cast the spell from step 1.
Resolve the spell from step 1.
Repeat.

Infinite artifact ETB

Infinite artifact LTB

Infinite +1/+1 counters on a creature

Infinite creature ETB

Infinite creature LTB

Infinite magecraft triggers

Infinite red mana

Infinite storm count

Infinite creature tokens

Displacer Kitten

Molten-Core Maestro

Storm-Kiln Artist

Campus Composer // Aqueous Aria

Cast Aqueous Aria using Caetus, Sea Tyrant of Segovia's convoke ability by tapping creatures you control.
Displacer Kitten triggers, blinking Campus Composer.
When Campus Composer enters, Intruder Alarm triggers, untapping all creatures you control.
Repeat.

Infinite casts of a specific spell

Intruder Alarm

Invasion of Segovia // Caetus, Sea Tyrant of Segovia

Cast the copy of Aqueous Aria spell from exile by paying its mana cost.
When you cast that spell, Displacer Kitten triggers, flickering Campus Composer, which enters prepared.
When Campus Composer enters, Mana Echoes triggers, adding at least {C}.
Resolve the spell from step 1, creating a 3/3 Elemental creature token with flying.
When the token enters, Mana Echoes triggers, adding {C} for each Elemental you control.
Pay an additional {2}{U} to repeat steps 1 through 5 an additional time, this time adding {C}{C}{C} from the Mana Echoes triggers.
Pay an additional {1}{U} to repeat the loop again, adding {C}{C}{C}{C}.
Pay an additional {U} to repeat the loop again, adding {C}{C}{C}{C}{C}.
Pay an additional {U} to repeat the loop again, adding six {C}.
Activate Gemstone Array by paying {2}, adding {U}.
Repeat steps 1 through 5 and step 10 any number of times.

Infinite charge counters on a permanent

Infinite colored mana

Infinite colorless mana

Mana Echoes

Gemstone Array

Cast a copy of the prepared spell by paying its mana cost.
When you cast that spell, Displacer Kitten and Dovescape trigger.
Resolve the Dovescape trigger, countering the prepared spell and creating a number of 1/1 flying Bird creature tokens equal to its mana value.
Resolve the Displacer Kitten trigger, blinking Campus Composer // Aqueous Aria, which enters prepared.
Activate Phyrexian Altar by sacrificing a Bird token, adding one mana of any color.
Repeat step 5 until you have enough mana to cast the prepared spell.
Repeat.

Infinite death triggers

Infinite creature sacrifice triggers

Dovescape

Phyrexian Altar

Combos with "Campus Composer // Aqueous Aria"