What made the City of Glass so unique was that it was the perfect core of a warring state. All of its amenities and special features were tailored to military power.
The unique Glasswright Breeder Profession of the city formed a team of beast tamers capable of crafting armies of Glass Beasts, while the beast-taming facilities had characteristics similar to Sylas' own Hibernation Realm, helping them to grow faster and stronger.
In fact, the Glassirith Sylas had stolen from here the last time he stepped foot into this place was only dormant because the city hadn't been claimed yet. So long as Sylas claimed the city, not only could he build an army of beast tamers, but there was a ready-made army right here already prepped to be born.
Back then, Sylas had snatched up a newborn, and he didn't have the unique ability to accelerate the power growth of these Glass Beasts in particular.
