not much to say, this is my first guide, im a vayne lover and main, 258k masteries with her, started playing LoL around late s3, and started playing vayne beggining of s5, this is the build i found most viable, and if u have anything that u think im not doing right, plz notify me
note: i will be using alot the thing: "1v1"(ex: in 1v1 she cant kill you) that does not means this game is all about 1v1, it means u can kill her if she's alone, but u need to consider what are the consequences of doing that, and if u find their adc alone, just keep in mind that u have an opportunity but u must check if she's fed, what are his items, etc etc.....

i hope u enjoyed my guide, like i said, if im doing anything wrong just tell me

well armor seals ofc, since u will be facing an adc
marks i usually go full ad, u can take arpen tho(remember the point of runes in my opinion is win early game), if they have a rlly tanky team
glyphs u can go for mr, i usually go for full ad runes + armor and some attack speed like i do, but make sure u take mr glyphs if they have ap supp!(morg, karma etc)
quints: AD for sure, but u can also take attack speed but if u do that, go for ad marks
i say again the point of runes is make sure u win early

early game:the cutlass will help u sustain in lane, plus it gives u a slow, when chasing or escaping someone, boots of speed to be able to dodge and have more movement speed ofc(either killing someone, kiting or running)
core items: botrk- ofc, attack speed, lifesteal and fckin op passive, why not? ^^"
phantom dancer- i actually this one over firecannon or statikk, for the extra Attack speed, and more movement speed than the other 2, when near enemy champ
IE- no need to explain why this item is one of vayne's core items
boots- Attack speed, enchanted with furor, for better kiting
situational items: BT- i dont use it anymore since they gave mercurial scimitar life steal, but well, it still could work vs team with high dmg and no cc
sterak's gage- its a pretty good item, used too vs burst team with some cc, u can try it
GA- use it vs team with heavy cc and burst that even mercurial scimitar cant keep u alive
mercurial scimitar- i use it almost every single game, pretty good item, op ative, extra life steal, mr and ad, why not? xD
mortal reminder- its pretty good vs team with heavy heals( ex: mundo, soraka, swain, etc)
maw of malmortius- the mr, the armor penetration, the shield vs magic dmg :3 pretty good vs heavy magic dmg team
note: lord dominik's regard for sure, like i said unless they have heavy healing team, go for it, otherwise take mortal reminder

ferocity: fury 5/5 ofc, attack speed means more silver bolts proc, why not?
feast 1/1 since i dont find expose weakness good in vayne, since u will be the main dmg of ur team and not the support, i prefer feast or double edged sword
natural talent 5/5 more ad, that could be good, i never tried vampirism, but it could work pretty well early game
oppressor 1/1 the hell yea, this mastery works awesome with condemn, not to mention that it works with botrk too, so go for it
battering blows 5/5 arpen, nothing much to say
fervor of battle(keystone mastery) 1/1 this is the main keystone mastery for almost every ad carry, as well for vayne, u can sometimes go for warlord's bloodlust which works pretty fine tbh, or thunderlord's decree which works good, not the best tho, it helps u win early and burst out squishy champ late game
Cunning: Wanderer 5/5 thats a good thing, more movement speed, means more chances to stay alive i guess 3% movement speed even if its out of combat can save ur life
secret stash 1/1 i prefer this one, since assassin will be useless in bot lane, althought u can take it if u take vayne top, but since most of the times u will be bot, u will be doing 2v2, not rlly worth take it, runic affinity... errr... my junglers does not gives me buffs hahahah so nah, but secret stash increase duration of my pots by 10% and instant restore 15hp and 15mana instantly when used, yea thats good
Merciless 5/5 5% dmg when target is below 40% health? hell yeah, vayne likes it
Dangerous game 1/1 this one can save ur life, dont underestimate it :p

max Tumble first because it reduce its cd, which means more AA reset
silver bolts ofc, max it second, target's max health as true dmg, why not? ^^" u can max it first tho, but i recommend tumble
lvl ur ulti whenever possible and lvl condemn after tumble and silver bolts