Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
This is my build on Evelynn.
NOTE: You are a ganker! Your invisible skill at level one makes you THE team player. Make use of it.
First of we start with a Mana Crystal + 2 Health Potions, so you can go off for some harassing. After that you'll get your Boots and leave it this way first. Now start going for your Innervating Locket, to avoid any HP/MP problems when you are getting harassed/creeping.
This build never gives me any HP/MP problems as I make use of Innervating Locket [CD 2sec.]and spam Hate Spike. It'll give me 50HP/20MP every 2 seconds, which provides me with infinite MP for Hate Spiking. After that I finish my Sorcerer's Shoes for extra movement + Magic Penetration. Now I go for Guinsoo's Rageblade, the stacks are easy to get, just spam your Hate Spike and you have it permanently the stacks. [8 Stacks = 32% ASPD + 48 AP EXTRA]. So that's a pretty nice bonus.
From here on it's up to you whether first to get the Hextech Gunblade or Lich Bane.
The reason why I go for Hextech Gunblade is because with the Gunblade I get an extra Attack Damage and Ability Power and it also gives me the Unique Active slow skill, also an extra 300 damage is always nice to have. [With this you replace your Cripple Summoner Skill]
The reason why I get Lich Bane is, it gives you a 100% AP to your Attack Damage the next strike meaning with this end build it's 450 Attack Damage every 3 seconds. Definitely nice to have in my opinion.
Now we get Abyssal Scepter for some extra AP + Magic Defense Reduction to have some more nice damage.
As for the Masteries, I go for 21/8/1.
Offense for 5% extra damage + Ignite + Magic penetration mostly.
Defense for the dodge mainly.
Utility for Ghost.
One could argue to drop the dodge in Defense and go for Utility for Experience, but as a game drags on you'll reach lvl 18 naturally without any problems.
As for the Runes I go for Dodge + AP + Magic and Armor Penetration.
The dodge and AP and Magic Penetration is self explanatory.
The reason why I chose Armor Penetration is to easily harass low def heroes in the beginning, it really helps the 11 Armor Penetration from the Quintessences.
As you guys can see, this is different from the 500AP builds out there and I would like some feed back. :)