I don't think this is working as intended. I'm working on a new character and just did the moon strike. We had far and away more simultaneous enemies than I've ever seen doing that strike before. At the end, when we got wiped, it was five Wizards, six Knights (all on the ground) and a shitload of thralls and other dudes running around. I've never seen anything like it.
Never had the boss fight go on that long, either, for all the damage we did to the boss. We all bailed simultaneously after the wipe.
It wouldn't surprise me if they somehow fucked everything up with this patch.