Introduction

Evelynn got, with the correct build and tactics, a enormous damage output.
She can be played both as Attack Damage or Ability Power. But since i tried out both of them i strongly prefer the Ability Power build, she get's a lot more damage at late game.
The spell that makes this champion so good is her Shadow Walk spell, 'W'... The stealth.
With a stealth ability you can, for example, easily manage to escape, walk across lanes and through jungle without getting noticed, and most important, gank!
With this build and skill sequence it's important to know she is a really weak champion early game. I would recommend to not go for First Blood, ever... And wait until go for a kill until you have a nearby friend and you are at least LvL 3.
The real gameplay starts at LvL 6, when you choose your ultimate ability, Malice And Spite.
It is a perfect ganking ability, you run faster, hit faster, and you slow the enemy.
The passive of this spell is perfect for fast towerdives and good in teamfights because when you score a kill or an assist, you regain health which can help you to escape or clear out your next target.

Skill Sequence

I've chosen to make the sequence like this because of the Mejai's Soulstealer.
First i chose Hate Spike to easily finish off hostile minions and make some quick and easy money.
After that, i chose the Shadow Walk ability, so you can escape if your'e running low on health or getting an early gank.
Then when you get your Revage spell, the damage output spell, you can start hurt the enemies.
It is a really good finishing spell to get last hits for stacks to your Soulstealer or quick finish them off at tower when they are recalling.