From the updated patch notes: https://arcgames.com/en/forums/neverwinter/#/discussion/1231249/shroud-of-souls-preview-patch-notes-nw-80-20170515e-3-updated-may-23
Due to adjustments that have been made to various classes since the release of Castle Never, the Orcus boss fight has become more difficult than intended in terms of surviving his attacks. Groups must rely on quickly defeating Orcus before he has time to execute any of his abilities, which was not the original intent for the boss. As such, we have made the following adjustments that should make the encounter a more balanced experience: The amount of damage dealt by a majority of Orcus's abilities has been significantly reduced.
Orcus's various melee attacks now have noticeably different damage values from one another.
Orcus's maximum hit points have been increased.