The Blackflame Monks' armor, with its ashen cloth and black iron, symbolizes their allegiance to the god-slaying black flame. Their betrayal, abandoning their roles as guardians, likely stems from the allure and power associated with the forbidden black flame. Taboos, especially those shrouded in mystique and power, can wield an irresistible pull for those drawn to the darker paths of temptation and forbidden knowledge.