Found a trap that spawns these spiders that is VERY easy to get to:
Invis/ kill the 3 ravens (each one can be singled), go to the first 4-way intersection, invis/ kill the 2 static mobs there(watch out for the roamers), go straight again and after a few yards you'll trigger a trap (you'll see an emote reading you drew something's attention) and a hatchling will pop. They don't see through invis BTW. Did so earlier today (out of sheer luck, had no idea where to go), and got a strand of living chain off the very first spider pet killed in there :) Gated right away to turn in all the parts and get 2nd talisman, so I can't say how long it takes for a trap to be active again :(
FYI, there is another trap further down that passageway past the first trap. (following Solonnor's directions). Spawned another hatchling. I needed 2, both traps spawned hatchlings, and both dropped living chain on first kill.
Drop Strands of Living Chain as part of the powered clockwork Talisman (#2) quest. Also drop Razor Sharp Spider Fang, and A Venom Drenched Spider Silk, not sure what those are for.
These pop up every once in a while on the walkways around the zone. Don't see invis, rootable, no summon, easily killed. Just nuisance mobs put there to make it harder to group in the zone. Drop a couple tradeskill components though and one of the strands for the level 2 pok gate quest.