Why is there no one building attack speed on VI..........??????

Bloodrazor for the attack speed. Attack speed is crucial for stacking the armor shredding from the Black Cleaver and her W ability Denting Blows

Mercury Treads are good for Vi. She is constantly in the mix and wants to stick onto the enemy. With Merc Treads and the Dead Mans Plate slow they won't get away. Along with Black Cleavers speed boost and your gap closing abilities you will rarely be kited.

Hunter's Potion to keep her healthy. Mainly to keep the mana up.

Max Q first. Having a short cooldown on this is what makes Vi playable.
Max W second. The armor shredding is what makes Vi strong and makes her unduelable.

Cooldown is crucial for any Vi player. The more Q's you can land the more you will absolutely own them in a straight up duel or chase them down when they run. (They run alot) Thankfully her Ult is a massive gap closer and you have other tools from your items to stick to them. With full CDR Vi you will be surprised the amount of Q's you can land in one fight. (One critical chance rune just for fun)

Auto cancel with her E. Remember to keep farming. Vi can clear camps relatively fast to get you that gold and XP. By the time teamfights start happening they will not understand what hit them. Get your Black Cleaver.

Always try to use flash to gank a lane. Charge your Q ability flash towards enemy then hit them the charged Q. Large gap closer. You will be surprised how often a Flash Q will be a successful gank. Use it when you hit level 3 or whenever you can. Then continue farming till 6. Your flash is just sitting there wasting away in the early minutes most the time. Use it on a lane gank.

Try to combo the enemy or jungle camps with your abilities. Q into them. Auto once. Use your E to auto cancel. Auto once. Then E again. Then continue autoing. When done right it feels good. With attack speed it feels even better.

With the Black Cleaver, maxed W ability Denting Blows, and attack speed you will absolutely shred armor. Any enemy that is packing armor will immediately be at a disadvantage. You shred tanks and massacre squishies. You will have a hard time finding any champ that can duel this Vi. There is absolutely no reason to build excessive attack damage over attack speed. Her abilities and autos feel smoother with attack speed and her W and core item Black Cleaver stack much quicker. DONT BUILD WARRIORS ENCHANTMENT. Good luck.