A lot of people are complaining about Slark's Shadow Dance nerf in the 6.79 patch. Increased cooldown, decreased duration.
I think it's more of a buff, since it's no longer detectable by True Sight(Yes even by Towers and the Fountain).
At first, I actually was also thinking it was a rather stupid nerf. But accidentally on draft pick, I picked Slark, and since I'm a guy who practically reads the changelogs than most pub gamers, I knew about his ult.
Got to try him out, and by the Gods, just try to do your decisions correctly and you'll be owning. Got to fight with alternating active items, diving in with Pounce then Dark Pact, land a few hits. Then when thing's are about to get tough, or going to get disabled, activate Shadow Dance, and poof you're seemingly Invulnerable for 4 seconds(of course you can still be hit by Cleave, Global Ults, and such, but you will be granted Undetectable Invisibility, which will grant you to have your Ult's Passive regen for 4 secs). After that pop out BKB, and you'll still be hard to kill.
I got to say, Slark's more OP than ever. Given that his ult is used correctly. Which you can even use for escaping from guys like Spiritbreaker having dust...haha, I laughed at those guys using dust and sentries. They seriously need to read the changelogs.