With DK Control Undead or priest Dominate Mind or (lol) Mind Control. When controlled, they will cast on enemies instead, each cast debuffing their damage/healing by 5%.
Good stuff, yeah? I didn’t actually tell you this because it’s the best thing since conjured sliced bread or anything though. I’ve had one too many runs where a wipe or otherwise bad pull was blamed on affix handling, even though any affix mob that was casting, was on our side, so I decided you all needed to know this.
If you see affix mobs free casting, but you are mysteriously still pushing full numbers, I hope you now consider the mystery explained: They were free casting on mobs. If the pull still went badly, do you think that the mobs doing 5-10% less damage somehow worked against you?
(they CAN ninjapull though, in which case you may be absolutely right that affix handling caused a wipe)
Now, I’m expecting it won’t take even ten posts before this thread derails into “Incorporeal is a bad affix”, but I have nevertheless done my duty to mankind today.
They actually introduced it the first Incorporeal week, mostly because DKs and warriors could do so little to help with it. They made it so they could be controlled and so that some warrior throw could kill them, but the control part turned out to be bugged and the mobs cast too big a debuff, so they removed it again hours later.