Forty years later, Xykon slew (and zombified) the wizard Fyron Pucebucket, solely for Fyron's crown, in front of his apprentice Eugene Greenhilt. It was later revealed that the crown had no magical properties, and Xykon merely thought it looked "badass" but he was also greatly agitated by Fyron's condescending attitude for Sorcerers. This led to Eugene swearing a "Blood Oath of Vengeance" against the sorcerer, an oath that, with his death, has now passed down to Eugene's children, Roy and Julia. Xykon remembers very little of this event due to the sheer number of people swearing revenge on him for killing their loved ones in front of them, though he does tell Roy more details of the event upon taking back his crown, which Roy had worn on a necklace.
Xykon, at this point in his seventies then fell in with the goblin Redcloak, who told him of a plan to unlock one of the gates imprisoning the Snarl and use the monster to blackmail the gods themselves. However, the gate's defender, Lirian, defeated Xykon with a virus that neutralized his spellcasting powers. Redcloak restored Xykon's power by killing him with a spell that turned him into a lich, making him immune to the virus and later returning to successfully kill Lirian; an unexpected side effect was his inability to enjoy coffee any longer, with the death of others being the only thing that amuses him anymore.
Six months prior to the start of the webcomic, Xykon took over the Dungeon of Dorukan, killing the wizard Dorukan, in order to gain access to Dorukan's gate (Lirian's having been destroyed by fire when Redcloak fought her treant servants). Filling the dungeon with goblins, mercenaries and undead minions, he waited for his chance to unlock the gate.
Although his physical form was destroyed, Xykon's phylactery, made from the unholy symbol of his chief minion, the goblin high priest Redcloak, remained intact, allowing him to regrow his body over the next few weeks. He assembled a new, much larger army of hobgoblins (88 legions of approximately 300 hobgoblins each) and used them to reclaim his tower from an infestation of good-aligned creatures. He added many of these to his forces in undead form, most notably a zombie silver dragon which served as his mount.
He continued with his master plan to gain power, having turned his attention to the three remaining Gates located around the world, each of which could be used in the same manner as Dorukan's. Selecting the Azure City Gate as his next target, they successfully assaulted the outer watchtowers of the realm, eliminating the guards, imprisoning the paladin Miko Miyazaki (although he intended her to escape, allowing him to use her as a scrying focus to successfully determine the precise location of the Gate) and destroying the warning beacon before it could be activated. The army (approximately 30,000 Hobgoblins and several hundred zombies, ghouls and siege engines) arrived at Azure City and the attack got underway. Xykon's disregard for such things as tactics meant that they used a plan constructed solely by Redcloak to assault the city. This mainly involved using three decoy Xykons, a cowardly Eye of Fear and Flame leading the southern division, a Death Knight leading a charge at the breach in Azure City's walls made by Redcloak's titanium elementals and a Huecuva (undead cleric) holding position in the rear; all three are humanoid skeletal creatures that look no different than a lich, to the extent that Redcloak gave them colored pendants to tell them apart. The real Xykon was flying towards the castle on a zombie dragon, under a Greater Invisibility spell.
After Sangwaan, Azure City's seer, revealed him with a True Seeing spell, Durkon dispelled his invisibility. Xykon's dragon grabbed Sangwaan and threw her off the tower, then Xykon made several passes over the battlements, but was warded off and then assaulted mid-flight by Roy with his Starmetal sword. After unsuccessfully trying to talk Roy into giving up the attack for a later, more epic final face-off, he destroyed his own mount with a Meteor Swarm, sending Roy falling to his death. He then flew off under his own power, using the Overland Flight spell he had cast earlier. On the way he recruited Tsukiko, a prisoner released to defend the city, who told him the location of the throne room where the rift is located. Upon entering the throneroom however, he found that it was heavily guarded by the Sapphire Guard. When the Guard attempted to attack him, using their sheer numbers to overwhelm Xykon, the lich responded by using a single Symbol of Insanity inscribed on a rubber bouncing ball to drive almost the entire Guard into madness, attacking each other, and proceeded to casually destroy the rest. However, while Xykon was gloating over the success of the Insanity superball, all the spirits of the slain paladins ascended and took on new forms as 'Ghost-Martyrs' alongside the spirit of Soon Kim, Founder of the Sapphire Guard. Faced with a massive battalion of spirit warriors and an even more powerful foe in Soon, Xykon was rendered speechless. In danger of being overwhelmed, Xykon was rescued by the arrival of Redcloak, who told the lich to focus on Soon Kim's spirit while he dealt with the others. Realising that Soon knew about his phylactery, Xykon attempted to get Redcloak to leave, but the pair were swiftly incapacitated. Only when Soon was distracted by the arrival of the delusional Miko Miyazaki was Xykon able to escape, carrying Redcloak with him. After escaping the destruction and healing themselves, Xykon and Redcloak proceeded to proclaim that Azure City was under their rule. Xykon was later seen casting a Cloister spell over the city wearing Dorukan's headband.
He is at Epic Level (21+), as he points out he is at least 7 levels higher than Roy (who is level 13 minimum, probably 14), with Roy himself having stated that Xykon is at least 21st level considering that he needs an epic feat to cast an epic spell such as Cloister.