This slime and the other 2 (semi) named slimes ('a putrid pile of flesh' and 'a pile of swamp bile') in PoDisease have a chance to drop Etheral Parchments.
From my countless hours of being in PoDisease and killing these off when they are up, I'd say the order of Eth Parch drop rate is: 'a pile of swamp bile': common, almost all the time. 'a putrid pile of flesh': uncommon, maybe 1 out of 3 kills. 'Rankle': rare, perhaps 1 out of 5 kills
I killed this fella in a rather tricky solo fight. Saw him up and I think "Oh, a named! And he's dark blue (I was 55)." So I decide as a druid that my best shot to take him is to charm the rat next to him and have my pet wear him down as I dot. Unfortunately, it was a pestilent rat that was too high for my Call of Karana spell, and I ended up with aggro from both of them. I tried root-rotting for a bit, but even with KEI that was going to leave me OOM before the fight was over. Then I noticed another little rat hanging around. . . I had enough mana to charm him and send him against Rankle while I focused on keeping everything rooted and NOT killing me. The buffed rat took out the weakened Rankle and I was rewarded with an empty loot window. I was really hoping for my first parchment, but I'll settle for the satisfaction having taken my first named solo in the planes.
I just had round 2 with Rankle. This time I was level 56 and so was he. I was much better prepared for this fight and the only tricky thing was pulling him from a mass of other goos and rats, but somehow I weaved through with no adds. I charmed a feeble rat to wear him down to 33%, then root-rotted him the rest of the way down.
Heh, there's no use in looking for this guy. I've seen regular orange goos that have like 25% more hps than the rest and every time I kill one it drops a parchment. I don't even see why they put him in the game unless he drops a quest item or at least some kind of good equipment, he's rare enough to be dropping something at least.
He popped near the bone wall, I solo'd him by hate kiting with scoriae and a charmed rat. After a sunder every scoriae hit for full 688, dropping him about 4% each time so you can estimate his hp's. Enraged and almost ate my poor rat :(
A bunch of easy mobs around 54 and such drop etheral parchments such as the wraiths in PoN and I think I've gotten them off gyrating goos and rats in PoD before.
You are thinking about Relak not this guy, this guy doesn't pop in caves. And the guy he was talking about, probably Rythrak, another named rat in cave.
I saw him 1st day PoP came out dropped an etheral parchment and a 2nd time nothing If he has anything at all it sounds rare... :P i got the parchment to and i got a lvl 61 lull song :\