This is why you filter what "recent topics" you get on the front page, so you don't have League of Legends-threads popping up when you only play WoW.
Anyway, Lee Sin is a perfectly fine assassin. If you use his Q smartly, or even wards and W, you can just zoom right onto people, or shield wards to get close to people fast, and then beat their face in.
I do have to say though, a fed Talon or Kassadin is some scary stuff.