A monstrous, serpentine creature, Kastraliss is one of the servants of the Darkest Faerie featured in the video game. Not much of him is shown around the Neopets site otherwise, though in the comics of the Defenders of Neopia, it seems he can be summoned by a small, green statue. In the Darkest Faerie game, he was the cause of the sickness that the swampland village of Bogshot was experiencing. Tor and Roberta defeated him, and gained the black bogberries, the cure for the illness. 1000 years before the time of the game, he was defeated by the Altador council, and fled to Bogshot.
Neopets: The Darkest Faerie
A thousand years before ago The Darkest Faerie was first defeated, Kastraliss made home in the swamps south of Meridell after he was driven out of Altador. He made the citizens of Bogshot ill, and Tor and Roberta run into him when searching for the three ingredients for the antidote.
He is fought from a circle of stone platforms in the swamp where he can attack from inside or outside the circle, and can blow toxic green gas or lunge at the player's character. He can also hypnotize and paralyze the player and preventing them from dodging his next attack.
As Kastraliss takes damage, he'll start destroying some of the stone platforms. When he is defeated, the purple clouds in the sky retreat, and Tormund and Roberta defeat the other monsters, and free the rest of the lands from the clouds.