It was already replied by Agatio, Occult wasn't nerfed.
As it was said you need 100% if you want it to proc 100% of the times, thats pretty obvious.
If you tested 10 times and you got 9 out of 10 with 90%, thats pretty cool and yes, not 100%, obvious once again.
Now i'm locking this cuz people aren't bothering with the topic anymore.