Feldon 
A selection of Velious raid mobs have been doubling up on Area-of-Effect attacks since the expansion’s launch nearly one year ago. Atan (of Unrest) summed up the issues:
Condition 1: Modifieable timers line up such that a mob casts 2 different abilities simultaneously.
Condition 2: Ability that normally comes ever 40 seconds comes twice in a row with no delay.
Seems they are both bugs to me, but condition 1 is probably just a result of your design.
Maevianiu is getting serious about addressing the AoE double-casting by raid mobs in Velious raid zones and had these responses:
I cannot speak on Condition 1, I’ll leave that to the designers.
However, Condition 2 is definately a bug, and I’ve been chasing it for a while now and frankly. I cannot make it happen.
So I’m adding in some extra logging to try to pickup on when you guys make it happen and see if I can track it down from there. I’ll post in this thread later today with the zone(s) the logging has been activated in and you guys and post when it happens in those zones and hopefully we can find the cause and get it fixed.
And, if you guys can find a way to make it happen please post it here it will go a long way to getting this fixed.
and:
The logging is now active for any instances started after the time of this posting on the “Throne of Storms: Hall of Legends [Challenge]” zone.
Update:
Logging is also enabled in Foundations of Stone [Challenge]
As per Maevianiu’s post, logging is enabled in HM Foundations of Stone too.
Looks like he edited that one in a bit later 🙂
My money is on “Time Warp” affecting the mob.
Condition 1 is a “feature”. Actually, I hate it too and I see this when named aoes, on consistent timers that were separated by 5 seconds or more, start to drift together (because of lag or latency or server or design) and eventually line up resulting in Impossible-To-Cure conditions.
How many people actually remember back in EQ1, when there was an issue like this, a GM would actually join your group so they could see the problem first hand. I really hate to say it, but what happens in a developer/controlled area is not what happens in the “real” world.