Champion idea: Volt, Bringer of Justice

Hey everyone! I'm relatively new to League, but I thought I'd try my hand at designing a champion, because why not? If anybody wants to help balance it or suggest scaling or tweaks, be my guest! Due to my lack of experience with every champion, this may end up feeling like an existing champ, so don't hesitate to offer corrections for that. Without further ado, here's my idea:

Backstory:

Born and raised in the upper streets of Zaun, Samuel Locke was given the best techmaturgical schooling his parents could afford with the hopes that he would bring true fame to the family of inventors. When Samuel was 19, his parents' prowess was recognized in the worst way: a rival inventor from lower Zaun hired the man known as Warwick to dispose of them. Heartbroken and swearing revenge, Samuel went into hiding, adopting the name of Volt and using a pair of hextech arm blades to start his own career as an assassin. He still hungers to be the one to bring justice to Warwick, but knows he has far to go before his skill surpasses the hunter's.

Abilities:

Passive: Minion and monster kills grant Volt +0.5/1/1.5/2% movement speed for 2 seconds. With each susbsequent minion kill, the bonus is added, with one kill worth of bonus speed decaying every 2 seconds.

Q: Volt fires one of his arm blades (skillshot), stunning the first enemy hit for 1 second and dealing a small amount of damage. Volt can stack up to two charges of this ability.

W: Passive- Volt's basic attacks grant stacks, up to four total. Each stack slows the target's movement speed by 1/1.5/2/2.5/3%. Active- Volt detonates the stacks on all surrounding enemies, dealing low damage and doubling the slow for 3 seconds.

E: Volt charges in a line (skillshot), ignoring unit collision and dealing moderate/low damage to all enemies hit. Volt gains true sight of these enemies for 2/2.5/3/3.5/4 seconds.

R: Volt teleports to target location and slashes all enemies around him, dealing moderate damage and slowing them for 1/2/3 seconds.