The Fanatic

"Madness can take many forms, but none so contemptible as man's belief in a mythology of his own making. A world view buttressed by dogmatic desperation invariably leads to single-minded fanaticism, and a need to do terrible things in the name of righteousness. This man is an animal - rabid, destructive, and incapable of nuanced understanding. He must be put down."

- The Narrator

The Fanatic is a wandering boss added in The Crimson Court DLC. He is a wandering boss, like The Collector and Shambler, and he will hunt down your heroes, should they wander into a dungeon bearing the Crimson Curse. He will not appear in the game until a town event occurs declaring his arrival. Once he is in the game he will randomly spawn somewhere inside the dungeon whenever you bring a party with Vampires in it.

If the game decides that the Fanatic is to appear during an expedition a special loading screen with his face will show when the Dungeon is loading. This is your biggest warning that he is lurking somewhere within.

In particular, if you have 2 or 3 heroes infected, the chance of him appearing are 20% and 33% at medium and high infestation respectively. If all four of your heroes are infected, there is a 75% chance at both medium and high infestation

Behavior
Upon entering battle, the Fanatic will always surprise the party. If you decide to run away from Fanatic, he will appear in the next encounter, fulfilling his promise to hunt "the Cursed" down. He will spawn in the two back ranks with his stake and pyre in the front rows.

During the first turn of the battle, he will perform "Sentence Rendered" on one of your heroes. This places them on the stake where they cannot do anything and take constant HP damage - every time any character takes a turn. The Fanatic has three turns per round.

While a character is burning the stake, he will use offensive attacks with 3 actions every round. His offensive attacks move him forwards and cause debuffs, while his buffs move him backwards away from the front line.

Loot
Drops Crimson Curse-related trinkets, such as the Ancestor's Vintage and the Coven Signet. Subsequent Fanatic defeats will yield gem loot and other trinkets related to the Crimson Curse.

Strategy
The Fanatic is a relentless and challenging foe, and beating him with a poorly-geared party is nigh impossible. As such, he should be prepared for whenever you venture into a dungeon bearing the Crimson Curse. Attempting to retreat without abandoning the expedition is hopeless, as the Fanatic will simply appear in the next encounter.

Being able to move him across the battlefield or target all four ranks is essential to this fight. Like the Hag, the Fanatic will start every round using "Sentence Rendered" to place a hero on his pyre if one is not there already, dealing damage every action until they are on Death's Door. Unlike the Hag, it is worth trying to free the burning hero as soon as possible - the Fanatic is highly durable and every action he spends using "Sentence Rendered" is an action not spent marking or damaging your party. "Strike the Heretic" and "Holy Stake" are both high-damage single-target attacks, with the later dealing extra damage to marked targets, so being able to guard and clear marks can go some way towards mitigating the damage taken.

DoT attacks - Bleed moreso than Blight - are highly effective, since the Fanatic has both three actions per round and the ability to boost his own PROT. As with the Hag fight, boosting the party's Dodge is also a viable strategy, giving you a chance to avoid "Sentence Rendered" and allow the entire party to deal damage. Stress is unlikely to be a significant factor during this fight, unless it occurs at the end of an expedition or during a Short quest where you cannot camp to deal with it.

Trivia

 * The Fanatic 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.