Interweaving
The moment he activated the Ironstone Oath, the originally active Creatons in the space quickly shed all their passion for changing Currere and turned into a cold and empty residue of reality with William as the core.
A gust of wind blew, and dense metal clusters inexplicably fell in the hall, making it look like silver rain.
This was the effect of completely activating the Ironstone Oath—creating a wide-area magic nullification domain that directly affected Creatons. It could rapidly deplete malleable mana before any spell was formed, turning it into dead metal and cold reality.
This was another magic nullification method that was different from the principles of the Silence domain.
William didn't understand why Aiur would give him this as a so-called trump card.