Slagor is a Skandian who is the skirl of the wolfship Wolf Fang. He and his crew did not go and fight for Morgarath, but decided to go raiding before the other Skirls and Jarls got back to Hallasholm, the capital of Skandia.
He arrives on Skorghijl claiming he thought he could make the crossing of the Stormwhite Sea because of a lull; he lost two of his men trying to make the crossing. After Will and Evanlyn's escape attempt, he offered to flog them, but Erak told him to mind his own business. Slagor and his men didn't leave Skorghijl with Erak and his men because their ship needed repairing from the damage it had took.
Slagor betrays Skandia by planning to bring one hundred and fifty Temujai led by Or'kam in three ships to attack the Skandians from the rear of their army during the battle between the Skandians and the Temujai. His plans are overheard by Evanlyn, who followed him after she thought he was up to something, due to the fact he looked 'shiftier' than usual. Before Halt and the others were able to devise a way of accusing Slagor without being shouted down or foiled, Slagor accuses Evanlyn of being Princess Cassandra, daughter of King Duncan, and tries to persuade the Oberjarl Ragnak to execute her, fulfilling the Vallasvow sworn by Ragnak. Halt talks the Oberjarl out of executing Evanlyn immediately, then accuses Slagor of his plot against Skandia and, with Will, finds proof of his treachery. They found this out by sailing three ships, the amount of ships the Temujai were expecting, to the island where the Temujai were supposedly waiting for Slagor. When they found the Temujai camping there, the Temujai immediately asked where Slagor was. This was proof that he was involved in the plan.
In Erak's Ransom it is revealed that Slagor had been beheaded for his treachery against Skandia in The Battle for Skandia. Though Princess Cassandra is disappointed upon hearing this news, everyone else agrees that it was an appropriate punishment.