Nyss was one of the first agents of the Sith active in the galaxy, and was performing missions before their existence had been revealed. In 41 ABY he was involved by Darth Wyyrlok to hunt Jaden Korr on the Unknown Regions.
Nyss was watching alongside Wyyrlok via a remote cybernetic eye the mission of the Anzat Kell Douro on the Frozen moon; when they discovered that he was killed Nyss was ordered to take care himself of the mission to track down Jaden Korr, that was disveled as a plot to infliltrate a brainwashed clone, called Iteration, on the New Jedi Order but the clone was instable and they ned more DNA of Jaden or of his perfect Community clone Soldier.
So Nyss departed from Korriban alongside his sister Syll and Iteration in stasis. After some time he tracked Jaden and the clone on a mysterious rakatan space station but here he was killed by his target.
Power and Abilities
Nyss was a skilled swordman and a lethal killer; more beware not-Force-sensitive he was able to perform an Umbaran tecnic that confond the senses of Force-sensitive people.