Flash + Protean Hulk + Cephalid Illusionist + Nomads en-Kor + Narcomoeba + Viscera Seer + Blood Artist + Kozilek, Butcher of Truth

Banned

How it works

Cast Flash by paying , putting Protean Hulk from your hand onto the battlefield and sacrificing it.
Protean Hulk triggers, searching your library for Viscera Seer, Blood Artist, Cephalid Illusionist, and Nomads en-Kor and putting them onto the battlefield.
Activate Nomads en-Kor by paying , targeting Cephalid Illusionist.
Cephalid Illusionist triggers, causing you to mill three cards.
If you mill Narcomoeba.
Nacromoeba triggers, putting it onto the battlefield from graveyard.
Activate Viscera Seer by sacrificing Nacromoeba.
Blood Artist trigger, causing target player to lose 1 life and gaining you 1 life.
Resolve the Viscera Seer trigger, scrying one.
If you mill Kozilek, shuffle your graveyard into your library.
Repeat from step 3.

In which brackets is this combo allowed, per Spellbook's Banned tier?

1–2 · Exhibition & Core

Spellbook classifies this as Banned — not for these brackets.

3 · Upgraded

Spellbook classifies this as Banned — not for these brackets.

4–5 · Optimized & cEDH

Spellbook classifies this as Banned — not for these brackets.