Mikaeus, the Unhallowed + Blasting Station + Hovel Hurler

How it works

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Activate Blasting Station by tapping it and sacrificing Hovel Hurler.
When Hovel Hurler dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect.
When Hovel Hurler enters, Blasting Station triggers, untapping Blasting Station.
Resolve the Blasting Station ability from step 1
Repeat.

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

1–2 · Exhibition & Core

Spellbook classifies this as Spicy — not for these brackets.

3 · Upgraded

Allowed in this bracket.

4–5 · Optimized & cEDH

All combos are allowed.