[{quoted}](name=only zhule,realm=NA,application-id=3ErqAdtq,discussion-id=zV7VhQ0E,comment-id=00090000,timestamp=2016-11-30T00:36:11.687+0000)
I think that a short-ish cooldown is fine. But i'm not sure that it really needs to be THAT short for her to work. something like a 4 second cooldown would still allow for dodging of skillshots and some useful positioning in fights, but wouldn't allow her a near constant chase/escape tool.
That might be true, but at the same time, her dash does carry interesting gameplay, and since the cooldown begins only upon hitting the empowered autoattack, it doesn't make for the best escape tool. If you want to cut down her pervasive chasing strength, taking out her passive would likely be the best option, as it doesn't carry nearly as much interaction, and if you want to make her less mobile overall, her base movement speed could also be cut down by 5 (she's at 330 right now, one grade above 325, the minimum for any champion).
[{quoted}](name=only zhule,realm=NA,application-id=3ErqAdtq,discussion-id=zV7VhQ0E,comment-id=00090000,timestamp=2016-11-30T00:36:11.687+0000)
All that said there are a lot of issues with Vayne right now, mostly that she has currently shed her "anti tank" role and now is just a burst ADC (with tools to still take down tanks)
This I completely agree with. Vayne is closer to a skirmisher in her playstyle and damage output, not an assassin, and that she gets to burst down squishies in three autoattacks or less is not at all healthy. Vayne's design is very delicate in that it's conditional on her taking some time to kill targets: too much burst, and suddenly all of her survival tools, i.e. her dash, her stealth, her hard CC, just remove necessary counterplay from her while she kills targets without them being able to react properly. Above all else, she needs to not have burst, and perhaps then her low-cooldown dashes might be more justified.