I do not agree with the undocumented changes to invulnerability that went through on patch 6.20
As of 6.20 on hit effects do not work on targets who are invulnerable. This change was not documented in the patch notes.
Here is a video of what it looks like https://www.youtube.com/watch?v=LO7Rl5CfcC0&feature=youtu.be
As you can see I'm hitting my vital spot on vayne but it isn't popping. This limits my options severely against champions with invulnerability spells such as Kindred and Kayle. I can really only choose to run away and I can't even do that because I would need to pop the vital for the speed boost to escape. This is very frustrating and I really don't like this mechanic.
I believe this is similar to a video cowsep posted a few days ago https://www.youtube.com/watch?v=970Il9rrPZA
and 
got too mnay nerfs"
) and is much weaker simply due to that. Meanwhile, Nidalee got itemization buffs at the MYMU and that helps alot with the nerfs she has received.
.. that was broken as hell...
against champs with invulnerability since he can no longer heal off them while they're invulnerable.