Chronology: ComicsMost powerful and dangerous of the Four Knights of Revenge, Shagon is a tall, strong demon wearing a blue metal vest that (like those of his fellow Knights) has Nerissa's seal on it. His long black hair resembles a nest of snakes, giving him a Medusa-like appearance. As a human he worked as a geologist doing research near the mysterious Mount Thanos. While searching for his dog, Miska, he eventually came across Nerissa who wanted a human as "material" for her right-hand man. Shagon represents Nerissa's hatred for Kandrakar and feeds on expressions of hate. His life essence was nearly absorbed by Nerissa in the final battle but he wounded her and reverted back to his original form. Despite the hatred he expresses he did not forget his feelings as a human about the transformed dog Miska. Shagon gets Will to hate him because of her loving Matt and Shagon teases Will, saying that he has Matt as a hostage. Shagon terrorizes Guardian families and Matt's grandfather in particular.
Chronology: Animated Series
In the episode "L is for Loser". Nerissa gained control over his mind, by using the hatred he felt for her as a weapon. Shagon's Power was fueled by the hatred his enemies felt, which he used to mock Will by implying that he had hurt Matt. Cornelia repeatedly urges Will to not allow Shagon to get to her.
In "M is for Mercy" Shagon attacks the gaurdian's families in order to increase their hatred, which he does sucessfully. He Takes particular joy in taunting Will, as he claims her hatred is pure and that he's enjoying himself too much. He also claims that he is so bad he hates him self. Will tries to appeal to his better judgement, which causes him to flee. This is possibly due to Matt trying to regain control of his body and make Will aware of the situation. Shagon assumes Matt's identity in order to spy on the gaurdian's and cause Will to hate him even more
In the episode "S is for Self", Shagon is in trouble of revealing that he is not really Matt when he Struggles to perform up to Matt's usual standard. Matt argues with Shagon that if he does not allow him to help he will blow his cover. Shagon Allows Matt enough control of their brain and body so he can rehearse with his band and relieve himself of suspicion. Matt almost manages to regain control several times in order to warn Will, Shagon realises she threatens his control over Matt so decides that he has to get rid of her. He convinces her he needs her help and Leads her into an ambush. Taranee and Cornelia show up in tim to help her. The Knights gain the upper hand and nearly defeat the Gaurdians. Matt, seeing Will in trouble, gets through by singing the song he wrote for Will (The Will To Love). Will realises that Matt is inside Shagon calls out to him, this gives him the strength to fully break free of Shagon and destroying his personality. Matt then uses his Shagon's power to turn the tables on the Knights of Destruction. Meanwhile Nerissa (who was watching the battle through a Fold) drains the Knights of their power to fuel the original Gaurdians CHYKN reverting Matt and Mr Huggles back to their original forms.
In "U is for Undivided", Matt regains his Shagon form from Lillian Hale, the Heart of Earth. He becomes one of the three Regents of Earth, who help protect the planet and assist the Guardians in their fights against evil.