“Find Mystic Carrion’s Servant” is a quest in Act 3 of Baldur’s Gate 3 that starts out seeming very straightforward before turning into a much more involved adventure.
Mystic Carrion’s hideout in the basement of Philgrave’s Mansion is guarded by a magical door. You can get the password during the “Free the Artist” quest, but if you’re like me and heading down this path before finishing that quest, you can lockpick your way through the magical door (because that makes sense, right?). You can also have a party member take the form of a small animal using Wild Shape and sneak through an opening on the outside of the mansion’s westernmost wall.
Mystic Carrion is busy serving the wealthiest denizens of Baldur’s Gate and doesn’t take much of an interest in you unless you ask if there’s anything you could do to help him. He has a zombie servant named Thrumbo that recently escaped, and he wants you to track Thrumbo down. He mentions that three other zombies also escaped and says that they might have some information on where Thrumbo went, but he only cares about having Thrumbo returned – for reasons that will become clear a little later.
Finding Thrumbo
Mystic Carrion doesn’t give you any hints about where the other missing zombies might be. That initially left me pretty frustrated, so I decided to raid Philgrave’s Mansion for whatever I could find. On the second and third floors are a number of other reanimated corpses, and they’ll attack you if you spend too much time poking around. Luckily, Carrion doesn’t even seem to notice if you kill them all.
On the third floor there’s a locked door that I couldn’t resist opening. The small room behind it contains a portrait that hides a note Thrumbo left for the other zombies. He explains that he’s going to find them a boat so they can escape Mystic Carrion and tell them to meet him on the beach just south of Philgrave’s Mansion.
I initially managed to find Thrumbo after reading that note, but if you do go in search of the other zombies, you’ll find them scattered about Baldur’s Gate. They all look a bit like thieves because they wear hoods and bandanas to hide their rotting faces. Lumbar hides in an alley near Basilisk Gate. Morbus appropriately wanders around the graveyard, and Sacrum hangs out just north of Beehive General Goods. All of them give you just a sliver of information about Thrumbo’s plans and whereabouts.
A mummy’s lair
On the western edge of the beach is a small house that contains a wardrobe. Thrumbo is hiding inside, and when you discover him he’ll explain that Mystic Carrion is an evil mummy lord who killed Thrumbo and the other zombies to raise them as slaves. He begs you to help him kill Carrion for good, which means finding and destroying his heart. You could turn Thrumbo over to Mystic Carrion and be done with the quest here, or you can forge ahead and put a stop to Mystic Carrion’s misdeeds.
First you’ll need to head back to the second floor of Philgrave’s Mansion. Behind a hidden wall panel is a ladder that leads down to a small workshop that Carrion uses. There you’ll find a book called A Mummy’s Memories that reveals Mystic Carrion has a secret lair in the Undercity Ruins. It’s not hard to find. Just fast travel to the Undercity Ruins waypoint and head north until you reach the Passageway. Going through that will take you to the Ancient Lair, which is filled with Ancient Servants, Crawling Claws, and Greater Zombies.
This fight is especially difficult because everyone in the Lair gets inflicted with Spell Rot and takes significant damage every time they cast a spell. After a lot of trial and error, I discover that there’s a broken pillar wide enough for two characters to stand on. Apparently Spell Rot is the fantasy equivalent of the floor being lava because as soon as you’re standing on the pillar, you’re free to cast to your heart’s content and the fight gets much easier. Once all the enemies are defeated, loot the room for gold and pick the lock on a hidden door in the room’s north wall.
Stopping Mystic Carrion
Inside the hidden room you’ll find a book telling you that Mystic Carrion hid his heart inside of Thrumbo. You’ll also find a small jar containing Mystic Carrion’s brain. He hid a handful of his organs around Baldur’s Gate, and if you find and destroy them all, he’ll be significantly weaker during your battle. His liver is locked in a gilded chest in that same room, and his lungs are in a jar in the Mortuary basement in the graveyard.
The next time you speak to Thrumbo, he’ll puke up a jar containing Mystic Carrion’s heart. A simple melee attack is enough to break any of the jars, but be warned: they explode on impact, so maybe go with a ranged weapon. Once the organs are destroyed, you can charge back into Philgrave’s Mansion to face off against Mystic Carrion and some more of his undead servants. This fight is in pretty close quarters, but Spike Growth, Fireball, and Turn Undead served me incredibly well. Mystic Carrion has some great loot, and Thrumbo will give you a small token of his undying gratitude for saving him and the other zombies.