The Prophet is a boss that appears in the Ruins, and, like other bosses, has three variations (Sonorous, Fulminating, and Gibbering).
Ancestor's Memoirs: The Prophet
“
Excavations beneath the manor were well underway, when a particularly ragged indigent arrived in the hamlet. This filthy, toothless miscreant boasted an uncanny knowledge of my ambitions and prognosticated publicly that, left unchecked, I would soon unleash doom upon the world.
This raving creature had to be silenced. But doing so proved maddeningly impossible. How had he survived the stockades, the icy waters, and the knives I delivered so enthusiastically into his back? How had he returned, time and time again, to rouse the townsfolk with his wild speculations and prophecies?
Finally, resigned to his uncommon corporeal resilience I lured him to the dig. There, I showed him the THING and detailed the full extent of my plans. Triumphantly I watched as he tore his eyes from their sockets and ran shrieking into the shadows, wailing maniacally that the end was upon us all.
The Prophet spawns on rank 4, with wooden pews occupying ranks 1, 2 and 3.
The Prophet always begins the round with Prognostication, a free action which marks one or two ranks (not heroes), and ends the round with Rubble of Ruin, another free action that hits the marked ranks. Rubble of Ruin deals extremely heavy damage, potentially taking heroes from full health to Death's Door in a single attack. Aside from these, he has one normal action per turn, during which he will use either Eye on You or Fulminate.
If a hero is heavily stressed (>50 Stress), the chance of him using "Eye on You" will be doubled or tripled for Veteran or Champion level dungeons, respectively.
Breaking the pews will reward valuable Consecrated Pews at the end of the battle, up to 7500 gold if all three Pews are broken. After defeating the Prophet, all remaining pews will disappear along with the potential reward.
Strategy
The primary risk of the Prophet is Rubble of Ruin, which can very quickly bring your heroes to Death's Door. Without proper damage mitigation, Rubble of Ruin followed by a Blight or Stun can easily lead to one or more heroes dying.
Debuffing
Because the Prophet only takes one real turn per round, debuffs are particularly effective against him. The Leper'sIntimidate and the Occultist'sWeakening Curse, when stacked, can quickly debuff the Prophet to deal almost no damage, thus removing the main threat of the fight. This gives the party not only enough time to kill the Prophet, but also to smash the pews for more money. An example party would be Arbalest, Houndmaster, Occultist, and Leper. Between Intimidate, Weakening Curse, and the Arbalest's Suppressing Fire, Rubble of Ruin will often miss; and when it does hit, it will do next to no damage.
Guard
A second strategy relies using Guard to funnel and reduce the damage of Rubble of Ruin. This is somewhat riskier than using debuffs, as Rubble of Ruin can hit multiple targets, whereas can only protect one hero. And secondly, due to the way works, if Rubble of Ruin targets both the guarding hero and the guarded hero, then both of them will get hit anyway.
One example team using this strategy would be The Wall, consisting of Vestal, Man-at-Arms, Crusader, and Leper. The Man-at-Arms can guard the Vestal if needed, while the other heroes all have very strong defensive skills and camping buffs, allowing them to slowly chop through the pews while supported by the Vestal's healing. Note that PROT trinkets are essential for pulling off this strategy on higher difficulties, since as mentioned previously, the Man-at-Arms can only guard one hero at a time.
Others
As with most bosses in Darkest Dungeon, the Prophet is susceptible to DODGE-based strategies. Also the Shieldbreaker's Aegis Scales can completely negate the damage from a single attack.
Team Selection
Preferred Heroes
Abomination - Can deal extreme damage when transformed. Can also solo the Prophet with the right setup.[1]
Arbalest - Deals great back line damage. Suppressing Fire can be used to further decrease the risk of getting hit by rubble.
Crusader - Holy Lance can deal great back rank damage. Bulwark of Faith can also help him mitigate damage.
Antiquarian - High DODGE. Note that Flashpowder in this case may be even more effective than Invigorating Vapours (-15 ACC versus +10 DODGE), but requires a trinket to be reliable.
Bounty Hunter - While Caltrops and Mark can greatly increase the damage Prophet takes, he requires a lot of support to survive the Prophet to begin with. That said, he has an excellent DODGE trinket in the Mask of the Timeless.
Highwayman - While he has great reach, he doesn't have any sustain and Pistol Shot deals relatively lower damage compared to other heroes.
Plague Doctor - Relatively fragile, but good back rank damage. Excellent DODGE trinket in Ashen Distillation.
Discouraged Choices
Flagellant - While the Prophet is weak to Bleed, the Flagellant is discouraged in general for the Ruins. Not to mention, many of the Flagellant's best sustain abilities are of limited use and impose heavy debuffs.
Trophy
After completing the Prophet's champion quest, he will drop one of his eyes as a Trophy.
If you have subtitles on, during the intro before the level, the narrator will describe the prophet as a "miscreant", despite the text on screen reading "degenerate". In fact the subtitles are different in other parts of this intro too.
100% Stun
Stress +11
100% Blight 1**
Stealth
Bleed
Debuff
Move
Guard to funnel and reduce the damage of Rubble of Ruin. This is somewhat riskier than using debuffs, as Rubble of Ruin can hit multiple targets, whereas 
Mark users.
