Breath of Fury + Savage Ventmaw + Phoenix Chick + Warcry Phoenix

Exhibition

How it works

Breath of Fury attached to Warcry Phoenix.
You control at least one additional creature that does not have summoning sickness.
An opponent cannot block creatures you control.
Savage Ventmaw does not have summoning sickness.

Declare Warcry Phoenix, Savage Ventmaw and at least one other creature as attackers.
Savage Ventmaw and Phoenix Chick trigger.
Resolve the Savage Ventmaw trigger, adding .
Resolve the Phoenix Chick trigger, causing you to pay to return it from your graveyard to the battlefield tapped and attacking with a +1/+1 counter on it.
Deal combat damage using Warcry Phoenix.
Breath of Fury triggers, causing you to sacrifice Warcry Phoenix, then attach Breath of Fury to Phoenix Chick, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Move to your next combat phase.
Declare Phoenix Chick, Savage Ventmaw and at least one other creature as attackers.
Savage Ventmaw and Warcry Phoenix trigger.
Resolve the Savage Ventmaw trigger, adding .
Resolve the Warcry Phoenix trigger, causing you to pay to return it from your graveyard to the battlefield tapped and attacking.
Deal combat damage using Phoenix Chick.
Breath of Fury triggers, causing you to sacrifice Phoenix Chick, then attach Breath of Fury to Warcry Phoenix, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Move to your next combat phase.
Repeat.

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

1–2 · Exhibition & Core

Allowed in this bracket.

3 · Upgraded

Allowed in this bracket.

4–5 · Optimized & cEDH

All combos are allowed.

How it works

Breath of Fury attached to Warcry Phoenix.
You control at least one additional creature that does not have summoning sickness.
An opponent cannot block creatures you control.
Savage Ventmaw does not have summoning sickness.

Declare Warcry Phoenix, Savage Ventmaw and at least one other creature as attackers.
Savage Ventmaw and Phoenix Chick trigger.
Resolve the Savage Ventmaw trigger, adding .
Resolve the Phoenix Chick trigger, causing you to pay to return it from your graveyard to the battlefield tapped and attacking with a +1/+1 counter on it.
Deal combat damage using Warcry Phoenix.
Breath of Fury triggers, causing you to sacrifice Warcry Phoenix, then attach Breath of Fury to Phoenix Chick, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Move to your next combat phase.
Declare Phoenix Chick, Savage Ventmaw and at least one other creature as attackers.
Savage Ventmaw and Warcry Phoenix trigger.
Resolve the Savage Ventmaw trigger, adding .
Resolve the Warcry Phoenix trigger, causing you to pay to return it from your graveyard to the battlefield tapped and attacking.
Deal combat damage using Phoenix Chick.
Breath of Fury triggers, causing you to sacrifice Phoenix Chick, then attach Breath of Fury to Warcry Phoenix, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Move to your next combat phase.
Repeat.