Story

The city-state of Zaun is a twisted realm of science and magic ran amok. The air is choked with pollution from the countless factories and magic labs that spew waste into the sky. As polluted as the sky is in Zaun, its subterranean levels are far worse. The waste products of Zaun's many different scientific and magical endeavors have flowed together in its sewers, mixing into a toxic and mysterious concoction. Rising up from this alchemical nightmare is a single plague rat. Unlike his un-evolved cousins, Twitch (as he calls himself) can talk and read and interact with the world as well as any of the other sentient being in Valoran. Twitch has come to the League of Legends to represent himself—the only one of his kind—on the Fields of Justice.
While Twitch's true motivations remain known only to him, his prowess in the arena is a matter of public record. As a creature of the sewers, he is able to blend in with the shadows and ambush an unwary victim of his choosing. He has collected a significant quantity of the toxic soup that collects in Zaun's underground, which he coats his crossbow with. The effect of being shot with one of Twitch's crossbow bolts is extremely debilitating. Even without his poison, he will outright infect those he chooses to attack courtesy of him being a plague rat. As an act of desperation, Twitch may rapidly unleash a flurry of bolts at his foes. He madly peppers the area he focuses on, though the damage is reduced.