The moment you reach the Lower City, you may encounter some of the Strange Beggars that are wandering around, and you may notice they appear to be undead.
You later get a quest called Find Mystic Carrion’s Servant after visiting Philgrave’s Mansion, which has you searching for a certain person named Thrumbo.
To get clues to where Thrumbo is, seeking out his buddies Lumbar, Morbus and Sacrum will be a necessary step to finding him.
All Mystic Carrion Servant Locations
Lumbar
Strange Beggar Lumbar is one of the first Mystic Carrion’s Servants that you will find as he tends to wander the alley between Basilisk Gate Barracks and Stormshore Tabernacle.
Speaking of Strange Beggar, Lumbar will reveal that the group had plans on escaping by boat, hinting that wherever Thrumbo is hiding, there is water nearby.
Morbus
If you continue making your way north from the alley where you found Lumbar, you will eventually encounter Strange Beggar Morbus at the Graveyard north of the Forge of the Nine.
Strange Beggar Morbus is not the brightest of the bunch and will only remember that he was told to head “Down the stairs” and go “across the sand”, which hints that this could be near the docks.
Sacrum
Heading to the north of Beehive General Goods will allow you to find Strange Beggar Sacrum, who will tell you to look for an abandoned house.
Strange Beggar Sacrum also mentions a wardrobe, which hints that you should search for one in an abandoned house that you find.
How To Find Thrumbo?
Putting all the clues together will hint that Thrumbo is hiding in an abandoned house, near a body of water that has sand nearby.
This is in reference to the docks to the east of the Heapside Strand waypoint and the abandoned house that Thrumbo is hiding in is Vonayn’s Home.
Heading into the home will result in it being empty but if you interact with the wardrobe inside, Thrumbo will come rushing out.
It is up to you whether you decide to hear Thrumbo’s story or push through with your deal with Mystic Carrion to retrieve the escaped servant.
Verdict
Thrumbo and his buddies attempted to make an escape after one of their other friends had been destroyed by Mystic Carrion.
The 4 of them split up and were given instructions by Thrumbo to meet up but after your encounter, things will change for them.
After you find Thrumbo, you have the option to help him put an end to Mystic Carrion or turn him in and complete the deal that you made.