Twitch

Strengths

Twitch's Attack Speed is among the highest in the game; try purchasing items with on-hit effects such as Black Cleaver or Wit's End.
Contaminate has a large range; apply as many stacks of Deadly Venom as possible before using it.
You can catch up to an enemy out of attack range with Venom Cask.

Passive · Deadly Venom — Twitch's basic attacks infect the target %i:OnHit% On-Hit, dealing true damage each second.
Q · Ambush — Twitch becomes Camouflaged for a short duration and gains Move Speed. When leaving Camouflage, Twitch gains Attack Speed for a short duration. When an enemy champion with Deadly Venom dies, Ambush's cooldown is reset.
W · Venom Cask — Twitch hurls a cask of venom that explodes in an area, slowing targets and applying deadly venom to the target.
E · Contaminate — Twitch wreaks further havoc on poisoned enemies with a blast of his vile diseases.
Ultimate · Spray and Pray — Twitch unleashes the full power of his crossbow, shooting bolts over a great distance that pierce all enemies caught in their path.

A suggested 5-lane lineup built around Twitch, based on hero partnerships and role synergy — not win rate.