Darkest Dungeon - Gibbering Prophet (Champion level Prophet boss)

Setup:
Occultist(Junia's Head, Demon's Cauldron)
Occultist(Wilbur's Flag, Demon's Cauldron)
Crusader(Cleansing Crystal, Stun Amulet)
Leper(Crescendo Box, Focus Ring)

The goal here is to make Rubble of Ruin do 0 damage with the two Occultists spamming Weakening Curse and take advantage of it to kill the pews. With Demon's Cauldron the Occultist hits 100% chance to land the debuff - note that a Debuff Amulet would also let him reach 100%. With his biggest attack taken care of, the only threats are his unlucky blight spam or stress damage. Any decent front-line classes would really work with two Occultists, but I chose the Leper for Bloody Shroud's blight resistance, and the Crusader as an emergency heal if I didn't want to break the debuff chain - even though missing one debuff to heal shouldn't be an issue. The Prophet also can stun with Eye on You, so one of the Occultists got stun resist, while the Crusader took some blight resist, and everyone got a Holy Water to help resist Fulminate at the start while the debuff stacked. At camp I used Zealous Vigil, Bloody Shroud, and Reflection.

I think two Occultists make this fight extremely safe, and would rather rely on it than trying to rush him down with buffs or a marking party, or by spamming Bolster. Since the gold from the pews isn't that much at this stage of the game, if I were to ignore them I'd probably use the same strategy but bring something like a Hellion and a Houndmaster instead of the melee classes. For the walk to the boss I used the backline Occultist as a healer, the Occultist in rank 3 to pull targets in and use Sacrificial Stab, and the Crusader focused on stunning.