It can be obtained from Dannig when bringing him VerisiumVerisiumA shooting star may bring great fortune., which drops on defeating Captain Hartlin, and is needed to progress Dark Mists.
Usage
The Verisium Spikes can be used near the waypoint of Journey's End in order to free Freya Hartlin by using the spikes on the Karui Totems around her and further progress Dark Mists.
Finally set free, Freya reveleas her true from as Tekaru, a trickster god, which also starts the quest ending Delirium encounter, where the player has to fight Omniphobia, Fear Manifest, who drops several Liquid emotion items on defeat.
Item acquisition
Verisium Spikes has restrictions on where or how it can drop.