Hello! Another day, another ADC guide. Vayne may not be the best champion right now with how many counterpicks there are in the botlane right now (Varus, Ziggs), but she's still super fun and good in the right situations.
Definitely worth mastering her.

Vayne is good into many tanks, and really good versus Kai'Sa and Ezreal, since she wins lane against them and also outscales. She is a late game pick. Good with enchanters like Lulu.

Vayne is a hypercarry, but unlike other hypercarries, she is not absolutely terrible in laning phase. Go for short trades by autoing twice and then using Q, procing both W and PTA, for a huge burst of damage. If you have an agressive support, don't be afraid to all-in when you see a window for it. If you have an enchanter, you can go for quick trades with a shield.
The enemy is on a timer to make you fall behind, while you only get stronger as the game progresses. Remember that you don't need to get a lead from lane necessarily

Use your ult defensively, to get away from a diver, or agressively, to start a fight and dodge the skillshots that will be thrown at you. Ideally, tou will have a frontline who starts the fight for you, but it's soloQ, so that may be asking for too much. She has the tools to outplay a lot of stuff, but you need to be good at her. Try to stick with your team and teamfight with them.

If you're behind, farm the sidelanes safely and scale into late game.

You will probably kill people in 4 autos by now, melting the frontline faster than any other champion in the game. Play it smart, dodge skillshots, and get those montage plays.