Activate Codie by paying {2} and tapping it, adding {W}{U}{B}{R}{G}.
Activate Codie by paying {U}, untapping it.
Repeat.
Once you have an arbitrarily large number of Codie triggers, you may cast any instant or sorcery spell by paying its mana cost.
Codie triggers for each time you activated its ability.
Resolve the first trigger, causing you to exile cards from the top of your library until you exile an instant or sorcery spell with lesser mana value, and allowing you to cast that spell without paying its mana cost.
Repeat step 6 for each remaining trigger.
You may also repeat this combo for each instant and/or sorcery card in your hand, and on subsequent turns.

Cast a subset of spells in your library

Infinite black mana

Infinite green mana

Infinite red mana

Infinite white mana

Codie, Vociferous Codex

Galvanic Alchemist

Training Grounds

Biomancer's Familiar

Activate Codie by paying {4} and tapping it, adding {W}{U}{B}{R}{G}.
Activate Codie by paying {U}, untapping it.
Repeat as desired, skipping step 2 on the final iteration.
Once you have an arbitrarily large number of Codie triggers, cast any spell by paying its mana cost, reduced by the {W}{U}{B}{R}{G} added in step 1.
Codie triggers for each time you activated its ability.
Resolve the first trigger, causing you to exile cards from the top of your library until you exile an instant or sorcery spell with lesser mana value, and allowing you to cast that spell without paying its mana cost.
Repeat step 6 for each remaining trigger.
You may also repeat this combo for each instant and/or sorcery card in your hand as mana permits, and on subsequent turns.

Zirda, the Dawnwaker

Activate Codie by paying {3} and tapping it, adding {W}{U}{B}{R}{G}.
Activate Codie by paying {1}{U}, untapping it.
Repeat as desired, skipping step 2 on the final iteration.
Once you have an arbitrarily large number of Codie triggers, cast any spell by paying its mana cost, reduced by the {W}{U}{B}{R}{G} added in step 1.
Codie triggers for each time you activated its ability.
Resolve the first trigger, causing you to exile cards from the top of your library until you exile an instant or sorcery spell with lesser mana value, and allowing you to cast that spell without paying its mana cost.
Repeat step 6 for each remaining trigger.
You may also repeat this combo for each instant and/or sorcery card in your hand as mana permits, and on subsequent turns.

Heartstone

Cast Aura Finesse by paying {U}, attaching Power Artifact to Codie and drawing a card.
Activate Codie by paying {2} and tapping it, adding {W}{U}{B}{R}{G}.
Activate Codie using the ability from Galvanic Alchemist by paying {U}, untapping it.
Repeat.
Once you have an arbitrarily large number of Codie triggers, you may cast any instant or sorcery spell by paying its mana cost.
Codie triggers for each time you activated its ability.
Resolve the first trigger, causing you to exile cards from the top of your library until you exile an instant or sorcery spell with lesser mana value, and allowing you to cast that spell without paying its mana cost.
Repeat step 7 for each remaining trigger.

Combos with "Galvanic Alchemist"