The "everyone dying" part of this is just the default thought.
With a bit of extra planning you could happily have paladins DI as many people as possible. In a 10 man (for my setup) this removes 4 people. 2 dead paladins + 2 di'd
Have the mages use invis if this lasts long enough for them to despawn.
Hunters get to FD.
I'm not sure if Rogues + vanish still works in these encounters but also an option.
That gets rid of 6/10 at least.
With alliance the druid can shadowmeld and most likely you will have another Nelf or two which you don't target with the DI.
So 9/10 are now out of the picture (for my raid setup anyway) and 1 is left to die. Might take a bit of timing on vent but if everyone knows what they're doing it wouldn't be hard at all. Warlocks can even help by killing themselves
You wouldn't even need to dps the 2nd target until after everyones re-entered combat as you'd still have a large chunk of the raid alive/ready to fight - Especially if you kept a holy priest as the cycloned mob and had some interrupters.
Now based on not having to dps the second target if you can kill the first mob in 15-20 seconds you could even possibly have a mage cast a portal before the fight to save people having to die. Although they would miss loot.
Just my ramblings anyway