Just read the latest patch notes:
Demonology
Dark Soul: Knowledge now increases the effects of Mastery: Master Demonologist by an additional 30%.
Hellfire's damage has been reduced by 20%.
Immolation Aura's damage has been reduced by 20%.
Was this a known nerf?
- - - Updated - - -
Also, was it known that Demonic Gateway no longer temporarily drop threat?
Demonic Gateways are no longer attackable once more and no longer temporarily removes threat from the user. The debuff from using a Demonic Gateway has been increased to 60 seconds (up from 15 seconds).