Codie, Vociferous Codex + Voltaic Construct + Heartstone

Codie, Vociferous Codex

Voltaic Construct

Heartstone

How it works

1. Activate Codie by paying 3 and tapping it, adding .
2. Activate Voltaic Construct 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 fascinating loop relies on turning Codie, Vociferous Codex into a self-contained mana engine, turning its traditional restriction into an advantage. Normally, Codie's activated ability costs four mana, but the presence of Heartstone lowers that activation cost to just three mana—allowing Voltaic Construct to untap Codie for one mana and generate infinite colored mana in the process. Because every single activation of Codie's ability triggers its cascade-like effect, you stack up a massive wave of free instant and sorcery spells waiting to be launched from your library.