1. Your heroes can and will constantly attract the Crimson Curse disease - you won't be able to prevent it no matter what. This is why you should collect all the bottles with The Blood you stumble upon during your missions. Additionally, constructing the Sanguine Vintners as quickly as possible will allow you to quickly generate a large supply of those valuable items.
2. The Crimson Curse can be cured by defeating one of the three main bosses of the Crimson Court DLC - the Baron, the Viscount and/or the Countess. Each time you defeat one of them, all of your heroes will be cured of the Crimson Curse.
3. In order to enter the Courtyard (aside from the first mission) you will need to get Invitations. Those are special items that are dropped by Gatekeepers, foes that appear in regular dungeons when your Infestation level is high. The level of Infestation can be checked in the upper left corner of the "embark screen".
4. You can collect Blueprints used to construct district buildings by defeating Veteran and Champion level bosses. Each one you take down will give you 1 Blueprint.
5. When constructing district buildings, try to complete those three as quickly as possible: Sanguine Vintners, Granary and Cartographer's Camp. The first one will allow you to generate 2 bottles of The Blood each week, the second will give you free food at the beginning of missions (allowing your party to take more) and the last will increase the effectiveness of the light system, giving bonuses to both "full light" and "no light" modes.
6. When venturing into the Courtyard, focus on using heroes that can cause Bleed. Most enemies that you will encounter there are vulnerable to Bleed (and quite resistant to Blight), making Hellion, Hound Master, Jester and the new hero, Flagellant, extremely effective against them.
7. Take all the provisions when starting a Courtyard mission. Courtyard areas are huge (several times bigger than Champion-level dungeons) and the provisions will be quickly used. You should monitor the level of food your team has - every hunger check without food will cause them regular and stress damage.
8. Trinkets increasing SPD and DODGE are useful in the Courtyard. Enemies have high SPD stats and their accuracy is quite low - of your characters have sufficiently high DODGE stats they won't even be able to hit them. High enough SPD will allow you to act before most stress dealers in the area.
9. If you want to avoid any contact with the Fanatic, take only 1 hero with Crimson Curse into a dungeon. This will prevent the boss from spawning, as he requires at least two such heroes to appear in the dungeon.
10. The fact that the Fanatic will appear in the dungeon your party has entered will be signaled at the loading screen - if the regular area screen is replaced with his angry face then it means that your party will most likely run into him.
11. You can avoid the encounter with the Fanatic even though his face appeared on the loading screen and you know that he is inside the dungeon. You can either complete your mission and leave before you run into him, or simply retreat from the dungeon (with the button in the upper left corner of the screen).
12. If you want to force an encounter with the Fanatic, bring 4 heroes with Crimson Curse into a dungeon. This gives you 99% chance to summon the foe, but on the other hand will cause all of your heroes to take double damage from his Pyre - be prepared for such a scenario.
13. Once you take out the Fanatic, he needs several weeks to respawn. This can be used to level up parties consisting of Crimson Curse characters - even 4 of them won't cause the enemy to spawn.
14. The DLC added two new provision types to the game: The Blood and Laudanum. The first one is used to interact with Curios in the Courtyard, as well as to satisfy the hunger of the Crimson Cursed heroes. The latter on the other hand is useful when an enemy applies "Horror" status to one of your characters - Laudanum can be used to get rid of it.
15. Some enemies (and most of the new bosses) are now capable of causing the "Horror" status effect to your heroes. When that happens, your hero(es) will take stress damage over time (similarly to Bleed and Blight). The effect is not that dangerous, but it can stack - when that happens, it can even deal 15 points of stress each turn.
16. When travelling through the Courtyard you must be prepared to fight with the Crocodilian. This mini-boss encounter takes place in multiple places throughout the Courtyard. The enemy is not that powerful, provided that you have the right party composition - heroes that can strike all positions and apply Bleeding effect are most useful here. Don't forget about Shuffle abilities - the enemy has low Move Resistance.