Originally Posted by
Anonymoose
Though Ultima is the "steel," I imagine the "Darkness" within is indeed the Heart of Sabik, poetically used by Hydaelyn since Ultima was acting under the machinations of Ascians through the Garleans. Doctaru is correct - the one time Sabik it was mentioned, Lahabrea said that he hid it in Ultima's core and that not even the Allag really understood what it was or how it worked. Described variously, it is a "bundle of Darkness" that contains the "most powerful spell in all of creation," the "ultimate magick." This core was described as a heart and as a sacred stone of Darkness. The Ascians' intent was that the power of the primals, trapped by Ultima and funneled to the enigmatic core, would restore and awaken its potential.
The name, Sabik, is the concrete connection to Zodarik, as it's the name of a star in the Ophiuchus constellation.