This hotfix went live on January 26th
◦Al'Akir's Lightning Strike damage has been reduced on 25-player Heroic difficulty. In addition, its effect duration has been reduced to 16 seconds, down from 24 in both modes and difficulties.
◦Slipstreams can no longer be used during the Al'Akir encounter.
Exactly one guild killed Al'Akir before that fix went live, Paragon.
So you were in Paragon?