AD Assassin Mid
If you're looking for a guide on how to play Evelynn, you won't find it here. What you will find, however, are a bunch of unique and not-so-unique builds for you to try out. I am also interested in hearing what you have to say after using them, so please leave a comment in the comment section.
Edit: The cooldown nerfs to Evelynn's ultimate have made her less viable in the jungle as a squishy assassin; her ganks have become a lot weaker before getting Deathfire Grasp. Right now, she is best in mid lane, where her early game damage output destroys most other mid laners. However, she can still be utilised decently as an AP jungler.
I recommend the AP Jungler build. In team fights, use your ultimate after a teammate engages, hitting as many enemy champions as possible; when your team goes in, Dark Frenzy to the opponent AD Carry and quickly finish them with Deathfire Grasp and/or Ravage. Continue to spam Hate Spike while attacking, and try to stay our of range of melee champions.
10 different ways to play Evelynn
Have fun with these builds
Remember: Always Get Blue!
More possibly coming soon...
How to play Eve:
Push your lane.
Grab an Oracle's if needed.
Dark Frenzy--> Hate SpikeX9000--> Ravage-->Auto-attack--> Agony's Embrace--> Dark Frenzy