Nyxator was a sea dragon sent to Magnamund by the God Kai to establish good as the dominant force on the planet. He was blessed by Kai for being the wisest of his disciples and was granted great powers which Nyxator encapsulated in the Lorestones.
Evil sea dragons sent by the dark god Naar infiltrated the dragons and wiped out all of the good dragons except Nyxator who fled to the core of the planet, where he remained until he was slain by Naar's champion, Agarash the Damned. His legacy lives on through protagonists Sun Eagle and Lone Wolf, who used the Lorestones to become Kai Grand Masters.
The planet Magnamund was the key to the victory of either good or evil in the material plane of existence known as Aon. The first creatures sent there were demi-gods of the God Kai who shed their immortality and took the form of giant sea dragons. Naar sent his own agents as dragons, and thus disturbed, Kai instructed Nyxator, the wisest of the dragons, of this growing danger and also gave him many powers. Nyxator gathered all of the good dragons, left the seas and built a civilization on land called Cynx. In the year 12,209 MS, Nyxator created the Lorestones to encapsulate the knowledge given to him by Kai for all time. Part of this wisdom was an abiding love for all living things.
The wisest of the Sea Dragons. In the dawn of civilization on Magnamund, Nyxator lead the loyal Sea Dragons out of the seas to establish Cynx. Nyxator encapsulated the powers given to him by Kai in the Lorestones. Nyxator took refuge in the molten core of Magnamund when Naar's minions killed his fellows and destroyed Cynx. He remained there for two millenia while Naar tortured the world to make it give up its refugee. In frustration, Naar sent "the most powerful of his avatars," Agarash the Damned. After securing his hold on Southern Magnamund, Agarash journeyed to the center of Magnamund to destroy Nyxator. Nyxator died after decades of conflict and watched as Agarash stole the Lorestones.
The dragons aligned with Naar emerged from the seas and made war upon Cynx for centuries. They rained fire on the land, and the good dragons were reduced from thousands, to tens, until all were killed except Nyxator, who fled to Magnamunds molten core with the Lorestones. For centuries the evil dragons decimated the land until they turned on one another and went extinct.  The dark God Naar was furious that Nyxator had survived, and for two millennia "the air was dark with steam and fiery dust", and the seas boiled and the land erupted, but he could not reach Nyxator. In his fury, Naar sent his greatest avatar, Agarash the Damned, to Magnamund. He journeyed to the planets molten core to battle Nyxator, and though the dragon dueled with him for decades, he was now several thousand years old, his strength failed him and he was slain. The last thing he ever saw was Agarash stealing the Lorestones he had so long protected.
In later books both Sun Eagle and Lone Wolf later used the power and wisdom of Nyxators Lorestones to become Kai Masters, and the quest to find them is a central storyline in the Lone Wolf gamebook series. Nyxator also came up in Lone Wolfs quest of the Magnakai, such as when he journeyed into the city of Zaaryx, the only surviving dragon city from the Age of Chaos, which was deep underground the modern human city of Tahou, to recover one of the Lorestones. At the end of Lone Wolf's quest to free his friend Banedon from the Darklord fortress of Kaag, he observes that the southern gate is built from the hide and bones of Nyxator.