vayne is one of the most powerful champions in the game. she is amazing early and can carry late game. I build her attack damage and attack speed but as you see if i get a trinity foce i will end up with 100% crit. I start off with a dagger just to help get a lot of farm. then i get my berzerkers greeves followed by a vampric scepter. i get the vampric scepter early so that i dont have to go back as much, i can just lifesteal my health back. I keep up my farm and then get a phantom dancer followed by another phantom dancer. some will say i dont get any attack damage until to late and that will hurt there push and 1v1 capabilities but with the attack speed and 60% crit you will be critting enough to make up for the lost attack damage, and you should be able to 1v1 a similerly fed attack damage champion unless its tryndamere. you should be killing almost all the creeps in each wave now and be able to start you infinity edge. just keep farming and getting an occasional kill or assist and finish your infinity edge. when you have your infinity edge you will be able to 1v1 almost anyone now, no matter how fed. just tumble(q), auto attack and if there a melee champ condemn them back into a wall or just back in the lane and by the time they get close too you they should be almost dead. if not tumble back and then auto attack. this ability order is the best way to kill the enemy and keep your health pretty high. for your 6th item you have some options, you can get a black cleaver if they have some armor, or you can get a trinity force for a bit of everything(tumble and trinity force are amazing together), if the enemy team has a lot of burst champs and you find yourself needing a bit more health go ahead and get a frozen mallet it will help you get those kills that used to barley get away with ghost. if somone on the opposing team is fed you can get a defensive item without having to worry about your offense. now you should have your last item but you still have some money so you buy elixers but you still have some money burning a hole in your pocket so what you can do with this build is sell your boots and get a force of nature if they have a fed ap person or you can get a trinity force if you didnt get one as your 6th item if you get one of these you will still easily have 450 movespeed plus your passive. so all in all a well rounded build you get 2.0 attack speed 300+ attack damage, 85%+ crit, and good movespeed. you can try other variations of the build to see what works for you.