Crypt Slasher Circle

I'm in the eastern portion of Varajar Fells for the first time right now, in the darkened area just north of the Battledepths entrance. Could someone enlighten me as to what's up with the large number of Crypt Slashers completely encircling a large number of non-hostile (ie, green name texted) Skeleton spellcasters?

poke'em with a stick you will find out

pull the slashers a few at a time, when you are ready aggro the greens and fight the boss, they will turn hostile

Im guessing (as I cant remember that area fully) that the spellcasters will become hostile as you engage in combat with the Crypt Slashers.
There are many instances in Eye of the North where this happens.
Another example:
-Drakkar Lake (The rabbits cave thing)

Ah, so it's a trap.

If you pull the slashers carefully the skeletons won't aggro. I recommend not aggroing them if you're trying to vanquish.

Its the bunny cave of Varajar Fells.

Sounds like a circle mosh.