two quest items i cant find. any hints?

[Lyoven]

i need lustered soul dust and sign of trace for two of my quests but i just cant find any of them
im killing those monsters described in my quest log (like humans, magical creatures, undeads and whatnots may drop the lustered thingie), but i've never got one.
im killing all kinds of these monster, from "green" to "deep red" named, in dungeons and outside, 'general' monster and elites ect ect.. but no luck.
noone i asked in game has ever gotten one of them either

so. any clue?

[+Tequila+]

Sign of Trace drop from either grave robbers or Hobs: Hobs can be found in Vine Tomb and Grave Robbers can be found in in Burning Hill. Lustered Soul Dust drop from the lvl 50+ mobs in Collapsed Prison.

[Lyoven]

off to hobs then!
they take a while to kill, and those poisoning plants around them are reaally bad, but meh

any chance you could spare a lustered soul dust? since i will get a piece as the quest's reward, i could give it back right away =)

[+Tequila+]

lol when i go back to prison ill let you if i get some. I dunno if doin quest is even worth it now since alot of the rewards have been bugged. The grind is really horrible...im taking close to a hour per orb since none of my quest are worth doing now.

[Destrus]

grave robbers are also in forest of mist on the side close to elderine, little lizardman and proc zone are around them

[rokaraged]

If your atleast lvl 30 you can just grab a party and get it yourself in collapsed its great exp.