I wanted to try out Jayce with the new essence reaver because i thought it would be pretty good with the mana and also the cooldowns on his non ultimate abilities for constant ability spamming. But when i got the item it doesn't work at all. I don't know if its a bug or if Jayce's R just doesn't count as an ultimate ability. This was really disappointing because i felt like it would be a really good item on jayce.
So, basically, you're saying that it doesn't give CDR to Jayce's R? I'm pretty sure that all transformation ultimate champions whose ultimate is available at level 1 is coded to have fixed cooldowns, similarly to Yasuo's E.
He meant that using the R doesn't give the CDR to non-ultimates from the new Essence Reaver.
in b4 buying 6 
on champs with 0 ultimates such as 
qq probably doesn't work with nimbus cloak, presence of mind, ult reduction cap ultimate hunter
Could it be because Jayce R costs no mana?
I just made a post about this also, the essence flare will not trigger if you cast anything before landing the next auto after ult on any champ i've tested, so if you were Ulting on jayce into hammer form and using Q as a gap closer then it wont trigger, only way is to ult, auto, then use ability. Can confirm it will work on jayce if you dont cast anything before auto.
