I just got done camping this about 20 minutes ago and the plans are dropped by Gharg Oberbord and the skeletal jester. Gharg seems like he takes over an hour at least to spawn. All of this takes place in a tunnel under the water along the beach in Field of Bone. When you go down to the beach through the ramp, turn right and follow the beach til you see a pillar sticking out of the water, thats where the tunnel is. Don't bother casting Endure Breath cause the tunnel isn't that long. The room he spawns in has a big red throne with snakes on it, you can't miss it. The skeletal jester spawned about 30 minutes to 1 hour after I first killed him. So if you see Gharg pop kill him, otherwise just kill the skeletal jester cause then it goes much faster if you are looking for more than one of the plans. Now the other thing you have to remember is everything in there is indifferent. So if you can get a high leveled person to help you with Gharg or the jester do it because if the skeletons still con blue to you others will help attack and trust me they are not that easy at all in mass amounts. :) They seem to be around level 25 or so from the damage they dealt out and from the hitpoints they have. But if a high leveler attacks the jester or Gharg none of the others will agg on him. The way i did it was i brought my brothers level 52 cleric in there and casted Banish Undead and 2 shots deals just over 1000 damage and that didnt kill them just to give you an idea on the hit points :) But nothing aggroed so all was well. I hope this helps alot, sorry i didn't write down locations, i was tired by the time i got all this figured out. hehe :)
I have to say that I agree with all of this *except* who drops it this item... Gharg Oberbord and the Skeletal Jester may indeed drop this item, but I just looted it off "a servant of Sythrax".
He is 31 and HT's for over 300 I beleive (Been awhile since a few members of my guild raided him to help a 30ish Shammy) and he's in this room in an underwater tunnel on the Northeastern portion of the zone in the water. In this room is a bunch of Skellys that HT and cast necro spells as well. All are blue or Green to me, a 35 paladin currentely.