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.
Masteries: I go with a standard 9-0-21 build, using the flash and ghost masteries.
Summoner spells: I use the standard Flash and Ghost, both to chase, to dodge spells, and to get out of ganks. i don't recommend getting Clarity because i usually don't have much of a mana problem.
Get Rod of Ages or Sorcerer boots first
Situation: It depends if you are fed or not.
get Zhonya Ring or Lichbane first
Situation: If they are concentrating you get Zhonya for unique active and if not then go for lichbane.
Pick the 6th item depending on the match
Situation: if everything is going alright and you just want to nuke them down.
Situation: if they are heavy tanks i recommend this item.
Situation: If their team have super MR then seriously get this.
Sorry if I didn't write that much but i'm up to suggestions and improvements. Please vote and comment.