There and Back Again + Blade of Shared Souls + Flamewright + Staff of Domination

Exhibition

How it works

At the beginning of your precombat main phase, There and Back Again triggers, putting a lore counter on it.
There and Back Again's third chapter ability triggers, creating a legendary 6/6 Smaug creature token and causing you to sacrifice There and Back Again.
Activate Flamewright's first ability by paying and tapping it, creating a 1/1 Construct creature token.
Activate Blade of Shared Souls' equip ability by paying , attaching it to the Construct token.
Blade of Shared Souls triggers, causing the Construct to become a copy of Smaug for as long as Blade of Shared Souls is attached to it.
Put the Construct token into your graveyard due to the legend rule.
When the Construct dies, it triggers, creating fourteen Treasure artifact tokens.
Activate seven Treasures by tapping and sacrificing them, adding .
Activate Staff of Domination's third ability by paying and tapping it, untapping Flamewright.
Activate Staff of Domination's first ability by paying , untapping it.
Repeat from step 3.
Once you have infinite mana, you may simply tap and untap Flamewright to get infinite Construct tokens, and then use its second ability to sacrifice them for infinite damage.
You may also use the mana to activate any of Staff of Domination's abilities.

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.