You will need to have completed all of Piercing the Darkness: A Very Fortunate Turn of Events in order to obtain this quest.
Ingredient amounts will vary wildly based on how many trackers you need to use to find your seeping shadows. Numbers will also be thrown off based on the required harvesting step. I'll give you the bare-minimum numbers that you need for this chapter of the quest series, and the rest will be up to you. :D
Since these quests are generally set up to delete quest recipes as you finish with a quest that needs them, you'll notice that when you accepted this, it gave you back the recipe for the Advanced Lightning Tracker Mach I again. You'll be needing it soon enough ...
You will need to travel all the way down to the coast and to where the skeletons are. Once you are near /way -212.94, 2.60, 65.03 you should be able to use track harvestables to find "mysterious object". The skeletons were made nearsighted, but nearsighted doesn't mean non-aggro, so watch your pathing. You will need 3 mysterious object, and, well, these things are ancient artifacts, so some will be broken and useless. Continue until you have 3 mysterious object in your bags.
You receive the recipe for the anti-illusionary libation, but at this point you don't have all the ingredients that are needed for it.
First, craft 1 Advanced Lightning Tracker Mach I. This will take: 11 splitfin dartfish, 16 hornbeam spruce log, 12 humming azurite, 10 coruscating coal and a workbench.
Then return to the Aurelian Coast (if you left it to craft), and use the Advanced Lightning Tracker Mach I. Sadly, it isn't powerful enough to find the seeping shadows nodes that you need.
Examine the M.A.G.I.C. that you should still be lugging around in your bags, and the quest will complete. You will also receive the popup to grant you the next quest.
Craft another Advanced Lightning Tracker Mach I. This will take: 11 splitfin dartfish, 16 hornbeam spruce log, 12 humming azurite, 10 coruscating coal.
Since you will need AT LEAST three of the Advanced Lightning Tracker Mach II's, you may wish to mass-produce 5 of the Mach I versions on this specific step, so you have them ready to craft into Mach IIs when you are instructed to make them. This is totally your call, and may depend on your resource availabilty at this step.
If you look closely at your journal entry at this step, it lists the zone as Aurelian Coast, so even though the quest helper doesn't repeat that you need to be in Aurelian Coast, you DO need to be in that zone to harvest these.
This will need the workbench, 1 advanced lightning tracker Mach I and the materials you just harvested (25 splitfin dartfish, 32 hornbeam spruce log, 24 humming azurite) plus 25 coruscating coal.
You will need at LEAST 3 of the advanced lightning tracker mach II in a moment, so this is a good time to make additional ones.
I forgot to get the text for the step information, but basically use the advanced lightning tracker mach II from inventory to complete this quest and get the next quest.
This is, sadly, the roughest step for squishies. The seeped shadows can be in several spots, (at last check) there are three up at a time, and other players can also be harvesting them before you get to them. Most of these locations are in the middle part of the zone and are likly to require a considerable amount of mob-dodging.
The basic process itself is relatively simple though - use the tracker mach II, head to the orange dot it puts on your map, harvest the seeping shadows node to obtain seeped shadows, rinse and repeat. If the tracker can't find anything, move a bit, so another node is in-range of the tracker's ability to sense.
In some areas, yes, there may only be a single way on foot to up to where you need to be, but there WILL be at least one walking path to each one.
You will need a total of the 3 seeped shadows, 3 empty libation container, 24 lunar mushrooms, 18 rockhopper meat, 75 coruscating candle and a chemistry table.
The empty libation containers come from Fen Fen in the Fabrication Hall and cost 12g each. The fastest way there while in the Aurelian Coast is to evac, then run to /way 456.93, 132.26, -483.85 and zone into Sanctus Seru.
Return to one of the BoL overland zones (I recommend Aurelian Coast, since you need to head back there at the start of the next quest chapter) and use all three libations.
You will receive "Effigy of a Knight of Shadow Haven", "Tegi Ritual Totem" and "Symbol of the Shissar Empire."
Examining it from inventory will complete the quest, grant you the Shadow Prospecting ability, and offer you Piercing the Darkness: Marketplace of Horrors I (<--link)