I've been trying to avoid venting my feelings on the future of the mage class on these forums, but rest assured, if this nerf goes through, I will definitely reroll a warlock.

It's like all the fun out of being a mage is being sucked out. Massive Ignite stacks, giant alpha strikes, Blizzard kiting, Flamestrike farming, all gone. But with a warlock, you get to make people hurt themselves and scatter clumps of people with your Seeds of Corruption, or let rip with your uber pets, or stun in AoEs while obtaining defensive procs from their attacks against you. All the while doing similar single target dps to mages or more. I simply don't see the point any more.

Of course, this could still be a hoax... any clarification would be greatly appreciated.

Tested some aoe right now.

It was only for a very short time, and its not very reliable, but...

At first i couldnt see a difference, then i found myself a healer gathered some mobs at Bone wastes (not sure exactly how many, around 10).
AE for around 395 each time. (the quite interesting this is, it hit for exactly 395 each time!)

Then i aoed 2 mobs from same area, 430-340 dmg. (here there was a difference in dmg each attack, as there should be).

Tried with 5 mobs too, and again i had different amoounts of dmg (430-450).

It wasnt a lot less dmg, and its probably too low a difference to say anything, but it looked a bit weird, especially that i got an exact dmg every single time i aoed the 10 mobs.

Well, I can see them reworking the code to put less burden on the server when AoE'ing past 10 targets. I'm sure when I'm doing zerg-control stuff, the server, client, and connection HAS to be burning up the cycles. The plan might have been to just get a single number when past a threshold of mobs and they goofed when they implemented it. Maybe tried to reuse code from something else (hence the unwanted behavior).

This would also explain why the reports are that Blizzard (and Hellfire) are not effected while Flamestrike is. They automatically get the same number across all ticks. Blizzard rolls once, then channels that amount. It was not effected (arguably the biggest offender next to CoC because of its kiting power when talented) because it was already doing what they wanted, so they left it alone.

That's my theory at least. All reasonable expectations point to this being a bug. After all, if they wanted to kill AoE farming, they would have nerfed Blizzard, which they didn't.

OK, tying this to the previous observation that low numbers get individual amounts of damage, while higher numbers all get the same damage, my money is on this being a bug related to bandwidth-saving.

It looks as though for n <= 9, each mob gets an individual damage roll. For n > 9, a single roll is made and split across all mobs. Then then forgot to make this roll scale with the number of mobs.

Thus, at 10 mobs, each is taking 9/10 as much damage as it should - a 10% reduction. For 20 mobs, each is taking 9/20 as much as it should - a 55% reduction.

If I'm right, you'll hit a 66% damage reduction at around 27 mobs - is this close enough for your "about 66%" and "about 20" to fit? It may be that the breakpoint is 8 rather than 9, which would give you 66% reduction at 24 mobs and 20% reduction at 10 mobs, which actually fits better with what you observed. Or it may be that the divisor is 8.5, or something odd like that. The point is that the numbers you post are consistent with a cutoff point in terms of mob number, after which a single damage roll is made and then divided equally between the total number of mobs.

Now, it could be that this is an intended nerf, but for now let's report it as a bug (after all, it's not in the notes), and hope that that's genuinely the case.