Originally the changes to Zilean in URF were for the old zilean. However since his W no longer reduces the CD of his ult, undying zilean is theoretically impossible. Right now in URF Zileans ability rotations are sluggish. When the old man is clearly meant to be a rapid fire mage in the mode. While I understand you're trying to reduce the possibility of perma-stun situations and such. The point remains that Zilean is now in a really bad spot because of the CD changes to him. If at most allow his Q and E to follow the 80% cdr aura. I mean lets be frank here.
Zilean's Q at rank 1 with 80% cdr is no more than 2 seconds at the least. Whereas champions like Karthus can rapid fire their Q's at .2 seconds?