Malgor is the overall third main antagonist of AdventureQuest Worlds and the main antagonist of the Shadows of War saga, succeeding Drakath and the Queen of Monsters. He is the Shadowlord and leader of the mysterious ShadowFlame Army who seeks to destroy the world by taking control of the Mana Core and the ley lines spread across Lore with the intent of what he calls "bringing peace" to the world. Malgor claims to be a hero trying to end the suffering of others when his actions are seen as anything but heroic.
Malgor was born as a Mumbler (a slime-like creature born from the negative thoughts of the Eternal Dragon of Time) that was ejected from the Timestream after his creator succumbed to despair in an alternate timeline following a series of unfortunate events befalling them that followed the Queen of Monsters' death, and appeared near the Queen's keep. Seeking out his creator once more and evolving into a False Wyvern and later a Twisted Wyvern, he traveled to Swordhaven, Shadowfall, and Battleon seeking the help of Victoria, Lord Brentan, Gravelyn, and Warlic on how to bring back his creator - the Hero, who was also the Dragon of Time. Unfortunately for him, no one helped him and he was at one point tortured by Gravelyn and Noxus. Realizing that he couldn't bring peace through reason, he decided to enforce violence and corruption upon others and sought to corrupt the ley lines of Lore. The more miserable he became, the stronger he became. Eventually he evolved to a humanoid body, crafted a new armor for himself, and took on the name of Malgor.
Malgor first appears during the players' raid to attack the Queen's fortress and end her reign of terror. He corrupts several villagers to his side with his Shadowflame magic, and when the heroes face him, he quickly subdues and captures them and brings them to the fortress where they demand to see the Queen. Malgor holds out her decapitated head and accuses them of being her slayers, making it clear that he sees them as a threat to him. As he tries to convince them to join his side, a new ally named Varga appears and rescues them. She informs them that in order to defeat him, they would need to gather many allies and recover their powers as the Eternal Dragon of Time. As they get busy recruiting many allies and slowly regaining their Dragon of Time powers, Malgor launches several failed attacks against several locations such as Arcangrove and Mythsong Canyon through his armies of Shadowflame Dragons and Shadowflame Trolls, respectively, attempts to recruit Dage the Evil, Nulgath, Gravelyn, and Drakath to his army but fails. One of the Twins, Xing, temporarily defects to him only to turn against him due to a failed attempt to control the demon Blight, and makes a futile attempt to steal the Amulet of Order from Mirror Drakath that is foiled by the combined efforts of the players and the Lords of Order.
Malgor next enlists Tyndarius, a former general of the Queen's Army, and leads the ShadowFlame Onslaught through the Plane of Fire, stealing Fiamme's powers as the Fire Avatar and transferring them to Tyndarius, making him the new Fire Avatar. Before he can deal the killing blow to her, though, she awakens Galanoth as the Fire Champion just in time for him to save her, and they and the players escape the corrupted Fire Plane with help from Abel, Jinx, and the other Elemental Avatars. As the players help people all over the world fight against the ShadowFlame Onslaught and save Kyron from his influence, Malgor reveals his plan to Tyndarius: to seize control of the Mana Core so that he can "bring peace" to Lore. Tyndarius is suspicious of this idea, of course, and, against his wishes, leaves to reclaim the Ring of Fire Islands upon hearing that the people of Lore are on the winning side. While the players, Galanoth, and Elius (who was Tyndarius' aide until they convinced him to see reason) fight Avatar Tyndarius and strip him of his Fire Avatar status and return it to Fiamme, Malgor finally discovers the Mana Core and begins to take control of it while announcing his plan to "free the world from its torment" and declaring himself as its salvation. Unfortunately for him, the Mana Core starts lashing out at him and all of Lore as a result of his actions.
Realizing that he has lost control over the Mana Core, Malgor heads to Crownsreach and steals the Queen's Heart, leaving Drakath to pursue him to the Queen's fortress. During a huge fight with him, Malgor blames the players for what is happening and shows them a vision of possible fearful future events, including Gravelyn's possible death in Swordhaven where her father Sepulchure was killed, Brentan accusing Victoria of being the new Queen of Monsters and sentencing her to execution, and Drakath musing about the players falling into despair and having to go back to being a pawn again, believing that they will be responsible for it all and intending to restart the world. Just then, he is interrupted by Drakath, who attempts to crush his soul only to discover he has no soul to crush. His former general, ShadowKnight Gar, bites him in the leg before all three disappear.
In the timestream, Malgor is stomping several Mumblers in his rage when Drakath catches up to him, having put the pieces of the puzzle together. It is revealed that Malgor lacks a soul and is nothing more than a raging voice donning armor as a form for himself. He challenges Drakath to put his best efforts into their fight as he prepares for battle. Eventually, Malgor escapes to a series of dead timelines that the heroes explore where they learn of his tragic past. After finally seeing how they managed to kill the Queen of Monsters, Malgor appears before them and attempts to corrupt them again, but is once again interrupted when a familiar voice calls out to them from the Mana Core that they recognize, resulting in his mental breakdown and causing them to realize that the owner of the voice is still alive and that the Infernal Army hasn't done away with her after all.
- His sword can be obtained by completing the quest "Shadow Medals: Defend the Village!".
- He is attracted to negative emotions, which is what he uses to offer those experiencing them a place in his service.
- He is vulnerable to the powers of the Elemental Champions, as seen when Gravelyn harmed him with her attack on the Krahen when he tried to corrupt her to his cause, and when Galanoth harmed him twice - one time when he awakened just in time to save Fiamme from being murdered by him, and again when he assumed his dragon form and did it to separate Tyndarius from Fiamme's Fire Avatar powers. He is also revealed to be weak against hope and positive emotions.