Castle Sol crowns the highest plateau of the Mountaintops of the Giants, an old fortress sworn to the Eclipse, the eclipsed sun that protects soulless demigods. Its garrison fell long before the Tarnished arrives. What remains is Niall, the veteran general of Sol, alone among ghosts. The Veteran's Armor description names him plainly : 'Worn by Niall, the veteran general of Sol. Niall was a lone survivor who commanded spirits to defend his long-passed master. This aging general could not die, nor did he have anywhere to fade away.'

What makes Niall remarkable, even among the immortal commanders of the Lands Between, is how he fights. Where Godfrey commands soldiers and Radahn commands an army, Niall commands the dead, every old comrade fallen at Sol stands again at his call, drawn from the snow by the shotel he raises. He is, in his own quiet way, a private spirit-summoner of the same kind the Tarnished is, and the Eclipse Crest on the castle gate is the same crest that adorns the Mausoleum Knights' shields. The cult that produces him is older than the Erdtree and quieter than the Frenzied Flame.