Camped these for 31 hours and still haven't got it. Got a twilight cloth mask and belt. They seem to be rare drops from frenzied, groaning, lithe, dark shadows which are the "named" spawns. The greater and lesser shadows are their ph. I was chain killing them and was able to clear the island.
Before I quit playing for a while I got these off one of the shadows in TS. Seems to me it was one of the "named" ones but that was about 6 months ago so don't really remember for sure which one it was. Have also gotten a twilight cloth mask and cloak there from the shadows as well. The twilight cloth items seem to be uncommon but not extremely rare from the track record I saw, but I may have had bad luck as well. Good luck.
These are better than the Twilight Sea Quested gear for Int casters... which are harder to get, since you have to get a Jewel (random drop) and three quest items (random spawns).
Lol, that is very true. I did a set of bard Twilight armor for my bard and it took for ever, and these are not too rare of a drop, and are somewhat up to level to where if you needed arms at that level this is a item to try to get.