BIOGRAPHY - page 2: SLAYMASTER-1720
Earth-1720 was ransacked and conquered by Susan Storm-Richards, the Empress Hydra of that dimension. The Slaymaster of that world served as her top assassin, along with her personal bodyguard Wolverine. The Exiles were a team of dimension-hopping super-heroes who fought to fix damaged timelines for the greater good. Several members were captured on a mission to Earth-1720 and reprogrammed to serve Hydra. Slaymaster led them in the field against their 
remaining comrades Sabretooth and Morph. Slaymaster's incredible skill allowed him to face and even overcome Morph and Sabretooth despite their mutant abilities. He only stopped when he overheard a broadcast sent through their Tallus communicator, indicating that the entirety of Earth-1720 would soon be destroyed if their mission wasn't completed. Slaymaster broke off his attack to warn Empress Hydra of the threat.
He found his empress in battle with another Exile, the Psylocke of Earth-616, defending Reed Richards against his errant wife. Elizabeth's past history with her reality's Slaymaster left her fear apparent on her face, something Slaymaster gleefully savored. Their conflict was cut short when 
the Empress and Wolverine intervened and stabbed Psylocke in the back, robbing Slaymaster of his kill. Despite the assassin's personal pride, he remembered his loyalties and passed on his warning to Empress Hydra. The trio of villains abandoned Earth-1720 to seek their destinies elsewhere in the multiverse. [Exiles (1st series) #92-94]
To Slaymaster, being deprived of a kill was the highest dishonor. He became obsessed with Elizabeth as "the one who got away" and fixated on killing her again when he had the chance. As Empress Hydra led her men through multiple realities looking for new recruits for her cause, Slaymaster sought out Elizabeth Braddock on each world. He killed all her defenders and associates, challenged her to a duel if possible, and slew her in combat. The Exiles' Psylocke happened to be on a mission to one of these worlds when Slaymaster killed her doppelganger, and the psychic feedback created a link which allowed her to see the final moments of her counterpart's life. She was too late to catch Slaymaster before he left that reality but, from then on, wherever she was, Psylocke would feel the death of every Elizabeth Braddock at Slaymaster's hands. [New Exiles #7-8]
Psylocke-616 continued to train to face Slaymaster, but she wasn't ready to overcome her fear yet. The Exiles' leader Sabretooth tried to deal with the problem himself by ambushing Empress 
Hydra's people on Earth-4321. He thought to catch Wolverine alone first, but Slaymaster sensed his approach and Creed lost the element of surprise. He was injured, and the Exiles' Cat came to his rescue before ultimately killing Wolverine. The Exiles and Empress Hydra's forces parted after that, wounded, but with nothing settled regarding Slaymaster's vendetta. [New Exiles #11-12]
On Earth-81114, Empress Hydra and her people intervened on the side of the local power players to oppose the Exiles again. Here, Slaymaster had his first chance for a rematch against Psylocke-616. Despite his pretenses of honor, Slaymaster stabbed her in the back before she even knew he was on the field of battle. He claimed he did so to occupy her telekinetic powers, so she would have to face him with skill alone. Still, when his wounded comrade Venger grabbed Elizabeth's legs to pin her, Slaymaster chastised him for interfering so that his victory would belong to him alone.
With her training and determination, Psylocke managed to hold her own against the spitting image of the man who once blinded her. She retained her cool, dislocated his arm, and deprived him of his weapons. Psylocke used his own blades to pin Slaymaster to the ground by his neck, and 
prepared to deliver the killing stroke. Facing his own death, Slaymaster begged for mercy. Psylocke granted him that mercy, and turned away from her fallen opponent. Slaymaster dislodged himself and seemed prepared to strike her from behind again, but Sabretooth arrived and grabbed the villain first. Seeing no other option, Slaymaster triggered the dimensional teleporter in his armor and fled to fight another day. [New Exiles #17]
As Empress Hydra and the others were dead, Slaymaster was free to pursue his obsession without distraction. He even found a version of himself who was lovers and partners with an Elizabeth. By killing himself, Slaymaster somehow absorbed his skills and power to become even stronger. In time, Slaymaster discovered Earth-616 as his Psylocke's home dimension, and traveled there to kill her brother, her Captain Britain, in order to draw her out. Psylocke foresaw this through the systems of the Exiles' Crystal Palace, and journeyed out to stop him.
Psylocke made herself seen around London, engaging Slaymaster's attention to renew their fight. Captain Britain also noticed when the fighting began, but Psylocke held him back to battle her demons alone. Slaymaster and Psylocke fought on the streets of London, and the duel did not go the way Slaymaster expected. Elizabeth's constant training and the lingering influence of all the 
Elizabeth Braddocks who had died at his hands gave her the proper edge to finish the fight. She even relieved Slaymaster of his teleporter, leaving him unable to flee when his courage abandoned him. Before the final strike, all the fallen versions of Elizabeth Braddock were made manifest, and together they delivered the killing blow against the monster who hunted them all. [X-Men: Sword of the Braddocks #1]