Talk:Vayne/@comment-8969250-20151008173331/@comment-24496127-20151015060714

Because attack speed grants her mobility, so buying Runaans on her is already a huge boon compared to others who just get attack speed. Her E is also her biggest nuke, and the ability to stack it on multiple people allows for you to nuke multiple people. Due to the way her E works, she also doesn't sacrifice nearly as much as most marksman when it comes to single target damage. She also can't orb walk at all, so just having tons of attack speed is almost mandatory for her to perform well.

Basically, she's been built to rely on her E, so anything that boosts the power of her E is also indirectly increasing not just an ability's potential power, but the entire champions potential power. To give it perspective, a Runaans on Varus would just add miniscule AoE, and the W isn't strong enough where applying it to multiple people makes a big difference. So while his W would do more with a runaans, the champion itself wouldn't get much out of it.

I'm sure there are people that can explain why Runaan's isn't built better than I just did, but that's the way I've always thought of it.

Vayne's a pretty good example of people finding insane single target damage much harder to deal with than weaker Aoe's. Although I suppose any assassin has been a problem at some point.