At the beginning of your combat phase, Ayara triggers, returning Scourge of the Throne from your graveyard to the battlefield, and giving it haste until end of turn.
Declare Scourge of the Throne as an attacker, attacking an opponent whose life total is higher than or equal to yours.
Scourge of the Throne's dethrone ability and second abilities trigger.
Resolve the second Scourge of the Throne trigger, causing you to untap all attacking creatures and to get an additional combat phase after this one.
Holding priority, activate Umbral Collar Zealot by sacrificing Scourge of the Throne, putting a +1/+1 counter on Umbral Collar Zealot.
Resolve the second Scourge of the Throne trigger from step 3, doing nothing.
Repeat each combat phase.
This clever loop puts Ayara, Widow of the Realm to work from the command zone, utilizing her combat trigger to resurrect Scourge of the Throne with haste directly into the fray. Because Scourge of the Throne grants an additional combat phase upon attacking an opponent with the most life, you can trigger its extra combat repeatedly. Before that extra combat resolves, you sacrifice the dragon to Umbral Collar Zealot's ability—which concurrently lets you surveil 1 to smooth your draws—preventing the dragon from lingering on the battlefield and instead leaving it safely in the graveyard ready for Ayara, Furnace Queen to reanimate it all over again in the next combat step.