"Let us hunt those who have fallen to darkness."

Those who main the ADC role in 'League of Legends' most likely have played Vayne at least once.  'Tumble', which lets her dodge and harass at the same time, 'Silver Bolts', which lets her deal massive damage with a satisfying sound upon landing three auto attacks, pinning an enemy to the wall with 'Condemn', and pulling out an oversized crossbow from her back to shroud herself in darkness... To many, she is one of the most unique and "charming" champions to play.

The enjoyment of playing a marksman champion comes from ① being able to avoid the enemy onslaught by constantly kiting and ② having the potential to carry the team by scaling into the late-game. In regards to this, Vayne's kit is more than suitable. And so, it was only natural that many players would be attracted to this champion. Even today, Vayne is unfavored in the current meta, and yet players still pick her from time to time to have a taste of the sweet adrenaline the champion offers in late-game teamfights... granted she can survive the laning phase. 

But currently, to put it simply, Vayne is trash. First of all, when Vayne is picked in an average day to day game of solo queue, glares will most likely be exchanged between her and her teammates. And the bot duo is almost always guaranteed to hug the tower thanks to Vayne's inferior wave clear capabilities; players will more often than not feel helpless as minion waves crash into their botlane tower one by one. Eventually, the tower will fall, followed by the destruction of mid and toplane tower, because the ally jungler had no choice but to put his focus on botlane. But even amidst this chaos, you can most likely observe Vayne still farming somewhere, minding her own business in the hopes of "scaling" into the late-game. With the changes to 'Doran's Shield', it's true that the duration of the laning phase increased significantly; and yet, she still stands in an awkward position in the current meta. 

So one day, Vayne decided she couldn't take it anymore. She then proceeded to evaluate the other positions outside of the ADC role to see if she could blend in somewhere else. She immediately crossed 'support' off of her list as her kit lacks the necessary utility. In the midlane, she feared that the mages might kill her in one burst. As for the jungle, it was possible for Vayne when Bloodrazor was overpowered, but as of now, it would be too unstable for our 'Night Hunter'. The only place remaining was the "battlefield" called toplane, where large-bodied but short-armed big boys fight it out.

■ Vayne in toplane is actually... pretty good?

Toplane Vayne is actually a greater threat than it seems at first. Her laning phase, which is her biggest weakness in her former lane, is quite good in this new environment. Even Darius, the champion notorious for beheading and feasting on the corpses of many hapless toplaners, is reduced to a mere porcupine of silver bolts when going against Vayne. As long as she avoids playing against Teemo or Pantheon, she will spend a relatively good time "nailing" most toplane champions. 

But in actuality, Vayne has always been a popular toplane pick. In comparison, she isn't too different to the more conventional toplaner, Jayce, as he is a champion that specializes in taking down the opposing tower as fast as possible to start snowballing. The only big difference between the two is that Vayne acts as the "tank slayer" by kiting near the frontline, while Jayce utilizes his explosive damage to burst down "squishy" targets in teamfights. 

The merit of Vayne being able to bypass her weak laning phase is enough for some players to consistently play her in the toplane. Around mid to late-game, as Vayne equips herself with one or two core items, she becomes a massive threat for skirmishes around her lane - because the opposing toplaner has most likely been denied CS; allowing Vayne and her team to snowball and eventually take the game.

■ She still suffers from weaknesses

However, there is a considerable handful of downsides to picking Vayne as a toplaner. The biggest one of them all is the fact that sending Vayne into the toplane instead of sending the more common tanks or bruisers can make for an unsafe team composition. A tank plays an important role of absorbing damage so that a marksman can reliably dish out damage in later teamfights. So in a way, having two ADCs in a team with no "meat shield" to distract the enemy can yield terrible results - the team will either be crushed without being able to withstand the oncoming onslaught, or have to frequently back off without being able to actively retaliate.

Toplane, in general, is a brutal and unforgiving lane. The place is very prone to ganks and a single misstep can cost you your life. But the desire to pick toplane Vayne is derived from her lane bullying prowess; and in order for her to do what she does best, she needs to frequently overextend to apply pressure. In addition, her base stats, as well as her item build, completely revolves around building damage, making her a favorite target for junglers; this, in turn, leaves her even more vulnerable to potential deaths.

In order for Vayne to overcome these weaknesses, ① Vayne needs to constantly apply pressure to her enemy and deny him of CS - to eventually snowball the lead to victory. Also, ② as long as Vayne avoids death from ganks in the toplane, her teammates can take advantage of the situation by taking leads elsewhere on the map. Of course, that is easier said than done. If someone is able to play like this with Vayne, they can most likely do much better with a more conventional champion. 

■ Why it's hard to balance Vayne

For skill-oriented champions, simply playing with numbers on the AP/AD ratio of a skill can bring balance to him or her. But for Vayne and other auto-attack based champions, who are all dependent on purchasable items, a simple change in ratios won't do; and buffing or nerfing their skill kits can severely break them. 

For example, in PBE, Vayne received what seemed at first to be minor buffs. Her 'Silver Bolts' increased in damage and 'Tumble' applied 2 stacks of 'Silver Bolts' instead of the usual 1. She also restored a portion of her lost health upon killing a target that she damaged. From this change, toplane Vayne ascended from being an "entertaining" pick to a conventional and destructive one. And as a result, Riot immediately rolled back the changes and once again proved to us how difficult it is to balance Vayne.

Although it was only for a short time, many summoners expressed excitement upon being able to play Vayne again as a strong champion. Many forums had explosive discussions talking about Vayne, and this showed how popular she still is. Although this is my personal opinion, I find Vayne to be the most fun out of all the other marksmen. I sincerely hope for the day Vayne returns to the Summoner's Rift, where she can tumble as much as she desires.