Baron

"They would arrive in teeming hordes, adorned in powdered wigs and pretension - seeking to slake their thirst on wine and indecency. As intoxication invariably took hold, innocuous frivolities would escalate to ever more disturbing diversions. Orchestrating the hideous affair was a hunchedbacked fiend who seemed to delight in proportion to the suffering he caused. I could have stopped him, I suppose, but I was a slave to my own appetite, and restraint would have rendered me a hypocrite. Narration_courtyard_loading_01.wav"

- The Ancestor.

Back when the Ancestor was hosting his festivities, one hunchbacked man in particular took it upon himself to set up entertainment that was enough to disturb the Ancestor himself. Like a cruel ringmaster at a twisted circus performance, he enjoyed hosting shows that brought as much laughter and delight to his audience as they brought pain and suffering to his performers. The sniveling little maggot of a man seemed to enjoy the attention he was getting with his performances, and like a bloated tick, he fed upon the attention and always hungered for more. Even after the Crimson Curse transformed the party goers into blood-thirsty monstrosities, he's still there to provide a show for the crowd at his victims expense at the end of a maze-like and sprawling garden. After he was infected by the blood curse, he became a bloated abomination, a grotesque larval abdomen terminating in the limited remains of his once-human form. His arms and hands have become fleshy whip-like tentacles much like the whips he once used during his performances.

Reaching the Boss
The Baron is the first boss fought in The Courtyard. The greatest challenge faced by the party, oddly enough, is not the boss himself, but the dungeon he resides in. It is a truly massive dungeon with nearly a hundred rooms and many locked gates requiring special keys looted elsewhere inside the dungeon and guarded by powerful foes. The dungeon itself can be split into four distinct areas, with the Baron residing in the final area.

The first area is fairly straightforward, appearing as a somewhat straight path with a few side rooms. Keep moving to the right whenever possible to reach the second area. Beware of Bloodsuckers and traps, but there are no unusual challenges.

The second area is more difficult, taking the form of a circle with the central path cutting through. In the centre is a locked door requiring a red key found elsewhere. To progress, either move down to find the key or go slightly above where the key is found to bypass the locked door entirely. Either way, a mini-boss will block the way to the third area; the crocodilian.

The third area is a central hub with a locked door, two wings above and below, is much more difficult, and requires multiple keys. Travel down to the bottom wing to find the blue key, then head up again to the upper wing to find the yellow one, but beware, another crocodilian guards it. Come back on the main path to unlock the central door to progress to the final area.

The final area takes the form of extremely difficult multiple looping circles with the final boss in the middle behind a locked door. Head up to find the key to the Baron, then take the central path around to unlock the door leading to the Baron.

One special mechanic of this map is that if you acquire the keys, you can abandon mission and the next time you go back, you will start the mission right where you get a key, every room you discovered last time will be revealed. Take note that your party still suffer from stress penalty, and the next expedition will still cost you the invitation.

A map of the area can be found.

Fighting The Baron Himself
The Baron is a disgusting abomination, relying on his massive health pool and a few new tricks. One of his new tricks is that you cannot heal while there is at least one Insect Pod. Upon entering the room, he will be standing there with three Insect Pods behind him. Once the battle begins, he will immediately use the ability "The First Act" to spawn the fourth pod in his place and hide among them. The pods themselves prevent healing, but are easily ruptured with a single attack. The main threat here is that each pod can contain Sycophants, or Supplicants, which will immediately attack the party. It is wise to pop each pod one at a time to reduce the danger to the party. Using a bleed or blight attack on a pod, confers the DOT to the bloodsucker residing within the pod.

Once the Baron has been found, he will attack with three actions per round. Once he is brought down to three-fourths health, he will use the ability "The Second Act" to once again hide inside Insect Pods. This is the same trick as last time, but with more dangerous enemies hiding inside the pods, such as Esquires.

Rupture the pods until he is found, and the battle begins again. He will use more dangerous attacks more often, but his weakness betrays him. Once he is brought down to half health, he will activate "The Third Act" and yet again retreat into Insect Pods, this time containing the most powerful Bloodsuckers.

Once he is revealed, the Baron will attack with his most powerful abilities until he is dead, but this is a minimal threat, as even his party wide attack "Crowd Pleaser" isn't capable of doing more than eight damage per hero. This being said, with 3 attacks per turn and a potential 11 damage on Necessary Discipline, he can do serious damage if he chooses to focus on one person, so bringing a high health healer, such as occultist or flagellant is recommended.

If you fail to destroy any of the pods after the Baron summons them (for whatever reason - you miss all attacks, you decide to take a turn off to heal your stressed-out heroes, etc.), the Baron will use the move called "Guests of Honor", which will immediately rupture all the pods, revealing himself and the extras. This is a very dangerous situation, as you will most likely face a massive onslaught of attacks from the boss and his minions at the same time, without having the comfort of killing them one at a time.

Trivia

 * The Baron is voiced by Youtuber/Streamer Baertaffy, whose longest and most popular series consist of Darkest Dungeon playthroughs, going well over 400 episodes and hundreds of hours of playtime. Baertaffy is also the voice of The Fanatic and the Viscount.
 * There are several Esquires and Courtesans in the background during the fight. They are obviously cheering on The Baron, as they will laugh when the wrong pod is broken or when a party member gets hit, and they will boo whenever the pod containing The Baron is broken.