Since D&D's logo generally sports a sort of gold and red, I see these as the new general's standard. Kinda gives a reason behind his entire army influenced by D&D figures. Im just guessing though cause I really like the D&D logo colors for a card.
Also I'm with Greyelephant. No one was living in that underground city, except the Drow and the other D&D characters Utgar sent through Blackscar, and Vydar's secret underground drilling project with his dozens of Soulborg. This new Kyrie might have been one of the lesser warriors, that are not as powerful as the big 6, and fell under the promise of untold power given to him by Lolth magic combined with Wellspring power.