It knew a lot, and it would know even more, as the one among its kin to "escape" inprisonment.
Powers: Haereticum was powerful, in a manner very different than its siblings. The Demon could create, out of simple movements of its two, six-tendril appendages, complex machinations and markings, symbols before language and meaning, that spoke the very laws of the world, even in those primordial times. Haereticum could conjur all form of protection and offensive maneuvers while facing the Sunguard that pursued the floating monster, easily countering their very simplified rituals. This was, in fact, due to Haereticum tapping into a form of energy that was not yet known by the beings that surrounded it, what would be known as Arcane energy, rather than the personal Anima of each being and those around it.
Defeat and Aftermath: No matter what they would do, the Sunguard could not bypass Haereticum's defenses, and its attacks were fierce and devastating. But thanks to being all part of the same Source, the Sunguard used their hivemind-like connection with each individual being, to finally defeat the Heretic: every primal incantation that one side used, the other would counter, and the Sunguard began a long, extraneus casting of their rituals, as Haereticum shielded itself from them all, without realizing that the Demon was being forced to enclose itself from its assailants. Long after it began, Haereticum had trapped itself in a tomb of spells and sorcery, leaving it unable to escape, for the very spells that it used to protect itself, now formed an intricate net against any counter, thus sealing the Demon inside. While Haereticum kept itself conscious, it could not see nor sense beyond its wall of spells, and the Sunguard hid the creature's tomb of rock and incantations deep beneath the ground.