Throne of Glass
From Labyrinthe Wiki
The Throne of glass, also referred to as The Nagrech, The Nagrech Crystal or The Crystal, lies at the heart of the Empire both physically, metaphorically and ritually. Its precise origins are somewhat unclear but it is known that it once sat at the heart of Ishma before being moved by the Laiu during the First Age as part of their plan to stop the terrible ritual war that raged across the face of the world at that time and threatened the destruction of all things.
Shaped, and thus given form, by a gentleman known as Oeldwych, it is what grants the Master of Primus the ability to affect the flow of faith through Primus such that all may believe as they wish without bringing harm to the world. It is said that the ancient spirit of the Wyld is trapped within and by being so trapped it imposed order upon the world. It is this imposition that Ikhala is said to rail against and destruction of the Throne of Glass is believed to be how he might complete the oath he gave, some might say rashly, centuries ago that binds him to his current existence. The oath to restore his dead tribe.
The Throne, whilst the largest piece of solid Nagrech is not the only fragment, the next largest piece is believed to be the Nagrech Blade once wielded by General Methac Woland. Similary fragments of Nagrech are used at the heart of the Empire's Nagrech Sinks to achieve, on a somewhat lesser scale, what the Throne of Glass does, in each of the cities.