Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight + Flayer of the Hatebound + Phyrexian Altar

Decks

How it works

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Activate Phyrexian Altar by sacrificing Flayer of the Hatebound
When Flayer of the Hatebound dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
When Flayer of the Hatebound enters, it triggers, dealing damage equal to its power to any target.
Activate Phyrexian Altar by sacrificing Flayer of the Hatebound
When Flayer of the Hatebound dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
When Flayer of the Hatebound enters, it triggers, dealing damage equal to its power to any target.
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.