Breath of Fury + Dragonlord Kolaghan + Lathril, Blade of the Elves

How it works

Deal combat damage using the creature that has Breath of Fury attached and Lathril, triggering Breath of Fury and Lathril.
Resolve the Lathril trigger, creating at least one creature token.
Resolve the Breath of Fury trigger, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to a creature token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Repeat each combat phase.

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.