Zassaliss was a large male adder and the son of Berussca. He lived in Brockhall, where he was bound at the tail to his siblings Harssacss and Sesstra by the mace and chain of King Sarengo. As Zassaliss was bigger and stronger than the other two, he became the leader of the trio in their hunts as he wore a golden crown sporting two black jetstones; this was a crown previously worn by Sarengo.
Zassaliss and his two siblings attacked and killed Plugg Firetail while the Freebooter was fighting with Princess Kurda. Later, Zassaliss fatally poisoned Shogg before being killed by Triss with the sword of Martin the Warrior.