Codie, Vociferous Codex + Thassa's Ire + Opalescence + Biomancer's Familiar

Codie, Vociferous Codex

Thassa's Ire

Opalescence

Biomancer's Familiar

How it works

1. Activate Codie by paying 2 and tapping it, adding .
2. Activate Thassa's Ire by paying 1, untapping Codie.
3. Repeat.
4. Once you have an arbitrarily large number of Codie triggers, you may cast any instant or sorcery spell by paying its mana cost.
5. Codie triggers for each time you activated its ability.
6. 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.
7. Repeat step 6 for each remaining trigger.
8. You may also repeat this combo for each instant and/or sorcery card in your hand, and on subsequent turns.

This clever engine transforms Codie, Vociferous Codex into an infinite mana generator and spell-launcher by turning it into a creature using Opalescence, allowing it to bypass its own mana cost for Thassa's Ire. To make this loop work, Biomancer's Familiar steps in to reduce the activation cost of Thassa's Ire down to just a single blue mana, making the untap loop self-sustaining off of the five colors of mana Codie produces. Once you have generated an arbitrarily large number of mana and Codie triggers, every single instant or sorcery from your library can be freely cast without paying its mana cost.