Discovery, Exploration
Now that you know what needs to be done to get to the Phylactery Vault, you just need to clear out enough Thayans in enough zones to make sure they cannot thwart your plans - and find more glyph keys so you have enough to pull it off.
After removing the skeletons and deathlock wights overseeing the pig pen, you discover that one of the pigs is much smaller than the rest.
Pubert taps into his Totem abilities that allows him to speak with animals is converses with the tiny swine and discovers that he is actually a halfling minstrel named Drevin who angered a Red Wizard who true polymorphed him into a pig.
Malice is able to use dispel magic to free him from the spell even though he unfortunately does not have any useful information regarding the Doomvault or any of the Thayans.
He briefly accompanies you as you move toward the next known Black Gate location where you intend to send him back to the Gatehouse and Syranna’s protection, all the while scribbling down what he sees as he’s promised to write an epic ballad about The Iron Company and their exploits in Thay and the Doomvault.
In the Black Gate room in this zone, you find a otyugh chained up and being fed a bunch of skeletons being watched by a wight and a deathlock wight, all of which you make short work of.
As luck would have it, the wight hasa glyph key not only attuned to to the Swine Run in the Blood Pens, but also to the Prison of Filth in the Far Realm Cysts. You use the Black Gate here to send Drevin to the Gatehouse after contacting Syranna using the nearby contact stone then use it again to transport yourselves to the Prison of Filth.
There you find a large group of unarmed skeletons that seem to just be standing, waiting on orders. You pass right by them without them seeming to have any notice of you. But in the next room you find, hiding among piles of putrid garbage, several otyughs which immediately attack you.