Advanced civilization

A vast empire that spans multiple worlds. It uses a specific form of application of the Arts that can be operated even by people who aren't fluent in the gnomish runes. They have vast floating vehicles and fortresses, and special suits that enhance their physical and elemental capabilities.

At a certain point Surtur, Garth and the Wanderer end up in territory occupied by this civilization. Garth ends up acquiring one of their suits, becoming a powerful elemental and all around combatant, and further sparking his interest in the Arts.

Later, the advanced civilization actually invades the local world. It is currently unknown how exactly this conflict played out.