Codie, Vociferous Codex + Necrotic Ooze + Pili-Pala

Codie, Vociferous Codex

Necrotic Ooze

Pili-Pala

How it works

1. Activate Necrotic Ooze using Codie's ability by paying 4 and tapping it, adding .
2. Activate Necrotic Ooze using Pili-Pala's ability by paying 2 and untapping it, adding 1.
3. Repeat as desired, skipping step 2 on the final iteration.
4. Cast any spell by paying its mana cost, reduced by the added in step 1.
5. Necrotic Ooze triggers for each time you activated Codie's 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 nonland card in your hand as mana permits, and on subsequent turns.

This ingenious loop transforms Necrotic Ooze into a one-stop engine by combining the activated abilities of Codie, Vociferous Codex and Pili-Pala in the graveyard. By repeatedly tapping the Ooze for Codie's hefty five-color mana injection and then untapping it with Pili-Pala's untap symbol to filter and generate extra mana, you can infinitely prime Codie's cascade-like trigger. Once your mana pool overflows, you simply cast a spell to trigger the piled-up cascade effects, letting you churn through your library and cast every cheaper instant and sorcery for free.