Near-Death Experience + Channel + Emergence Zone

How it works

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On the end step prior to your turn, activate Emergence Zone by paying , tapping it, and sacrificing it, allowing you to cast spells as though they had flash this turn.
Cast Channel by paying .
Activate Channel by paying 1 life, adding .
Repeat step 2 until you have exactly 1 life.
At the beginning of your upkeep, Near-Death Experience triggers, causing you to win the game.

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.