Soul of Windgrace + Waves of Aggression + Grand Warlord Radha + Golgari Rot Farm

How it works

Soul of Windgrace, Grand Warlord Radha, and at least three additional creatures you control can attack without taking damage.

Declare Grand Warlord Radha and Soul of Windgrace as attackers.
When they attack, Grand Warlord Radha and Soul of Windgrace trigger.
Resolve the Grand Warlord Radha trigger, adding at least five mana that you will not lose this turn as steps and phases end.
Resolve the Soul of Windgrace trigger, returning Golgari Rot Farm from your graveyard to the battlefield tapped.
When Golgari Rot Farm enters, it triggers, returning itself from the battlefield to your hand.
In your next main phase, cast Waves of Aggression from your graveyard for its retrace cost by paying and discarding Golgari Rot Farm, causing you to untap all creatures that attacked this turn, and to get an additional combat and main phase after this one.
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.