Armed with wit, charm, and his signature transforming hammer, Jayce lives to protect his native Piltover. Long before his nation called him a hero, however, he was a promising young inventor. When Piltover commissioned him to study a rare arcane crystal, Jayce discovered it could be used as a vast energy source. Eager to make a name for himself, he began developing a device to harness its power. Word of the crystal's potential reached beyond the borders of Piltover. Viktor, the machine-augmented scientist from Zaun, brought Jayce an offer - together, they could use the crystal to advance his ''glorious evolution,'' a vision of humanity fused with technology. Jayce refused, but the Zaunite had no intention of leaving empty handed. He effortlessly blasted Jayce aside and seized the crystal, incinerating the lab's meager security force as he left for Zaun. Jayce implored the Piltover government to respond, but the officials refused to support an act of aggression. He decided to act alone, realizing that if no one struck back, Piltover would never be safe.
Jayce returned to the lab to prepare for his attack. After intense research, development, and hands-on testing, he emerged with his crowning achievement - the Mercury Hammer. Weapon in hand, Jayce marched to Zaun and began his one-man assault. Viktor's acolytes rushed to stop him, but Jayce smashed them aside, fighting his way into the heart of the lab. Inside, Jayce saw the horrifying brilliance of Viktor's creations, all powered by the energy of the arcane crystal. He realized that his only option was to destroy the power source, but Viktor stood in his way. Though their clash left both scientists heavily wounded, Jayce managed a desperate strike at the crystal. He shattered it and escaped as Viktor's machines erupted in flames. When he returned home, exhausted but victorious, the citizens of Piltover hailed Jayce as a hero. He reveled in the adoration, but knew that his actions had drawn the attention of dangerous enemies. Now devoted to the defense of his people, Jayce is Piltover's best hope for a bright future.
''Trust me: if we're smart, Piltover can stand strong against any threat. Hey, I'm living proof.''