Vex is a female human melee fighter. She uses a two handed sword in combat to strike her enemies. She mainly focuses on Area of Effect damage with some single-target capabilities.
Innate: Cursed Blade - All basic attacks on champions increase attack damage and ability power by 2 per stack (increases by 1 every level up to max of 19). Stacks three times and lasts 5 seconds but if duration is let to run out deals 10% of champion max health.
Q: Cursed Strike - Strikes all enemies in range dealing 60/80/110/130/150 (+.7 per Attack Damage) physical damage and dealing full damage to first champion hit and half damage to rest of the champions. Deals half damage to minions. 8/7/6/5/4 sec cooldowns. 50/60/70/80/90 mana
W: Dark Rune - Creates a darkened rune on the ground that remains there for two minutes or until walked over by enemy champion dealing 60/90/120/150/180 (+.5 per Ability Power) Magic damage to surrounding enemies and snaring them for two seconds. Allies who run over the rune gain a small damage and speed increase for three seconds. 20/18/16/14/12 sec cooldowns. 70/80/90/100/110 mana
E: Shadow Strike -
Passive: Increases movement speed by 2/4/6/8/10% when running towards a champion.
Activate: Strikes a single champion or minion dealing 60/90/120/150/180 (+.8 per Attack Damage) physical damage. After five seconds, the target blasts out shadow energies, dealing one quarter of damage done to main target to every surrounding target near the main target. 8 second cooldown. 60/70/80/90/100 mana
R: Fury of the Cursed - Increases attack damage and ability power by 20/30/40 for twelve seconds. During that time all basic attacks cleave the area dealing half of the basic attacks damage to every minion or champion in the area. 100/95/90 sec cooldown.100/120/140 mana
Start with Doran's Blade for some life steal and get berserker's greaves. After get a warmog's to overlap the innate's damage so she won't be too vaulnerable late game as well as a Frozen Mallet. Get Bloodthirster and Infinity edge then Trinity force. Sell the Doran's blade and get Atma's last.
(EDIT: Thanks to Leyrann for ideas to improve. :) )