Mikaeus, the Unhallowed + Bloodied Ghost + Blasting Station

How it works

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Activate Blasting Station by tapping it and sacrifiicing Bloodied Ghost.
When Bloodied Ghost dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it. When it enters, Bloodied Ghost will put a -1/-1 counter on itself, removing the +1/+1 counter.
Blasting Station triggers, untapping it.
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.