Shuffling Horror

Perhaps a distant cousin of the Shambler, albeit corrupted even further by the Eldritch god below, the Shuffling Horror is the first of four bosses that Darkest Dungeon has. It has 2 moves in a single turn and 3 different attacks.

Behavior

 * If the Priest is left alive, the Shuffling Horror's attack pattern will remain always the same making it a very predictable enemy. Since both of Lacerate and Undulations have a 1 turn cooldown, he will alternate between each of them every one of his turns. Therefore expect the following succession of Bleed-Shuffle-Bleed-Shuffle for this fight.
 * Should you decide to eliminate the troublesome Priest, the Shuffling Horror will always summon another monster right away with Echoing Disassembly. Although coded to only use it if he is alone, it might be possible that it keeps using it every other turn after the summon, dealing heavy stress across the party.

Strategy
Shuffling Horror spawns with a Cultist Priest. If he is killed, the Horror will just summon another enemy, making it pointless. The better way to deal with him is to stun the Cultist Priest every other turn. To this end, the Plague Doctor can prove herself particularly useful, being able to stun both targets at once with the right trinket selection (i.e. Blasphemous Vial and Stun Amulet)

As the name indicates, this particular "boss" is especially adept at disrupting your hero's party order, shuffling them with Undulations. He has two actions per turn, does massive stress damage with Echoing Disassembly and inflicts bleed when Lacerating your party members. As common with most two-action enemies, debuffs and stuns will not be very effective. Bleeds, on the other hand, proc twice per turn making it excellent choice. Blights are slightly less effective because of higher resistance. Additionally, it might be a good idea to decrease the Horror's PROT with a mark, as he is fairly slow and the party has a decent chance to capitalize on the mark before it runs out.

It is recommended to bring Heroes who can attack from multiple positions (Bounty Hunter, Hellion, Grave Robber). Heroes like the Leper and Arbalest would be ineffective. Relying on both Man-at-Arms' and Highwayman Riposte skills is another viable strategy, as all of the Horror's attacks target the whole party.

Ancestral Trinkets
As the Shambler, the Shuffling Horror carries with him Ancestral Trinkets. However, since only one of each trinket can exist in the player's inventory, when they are all obtained, the Shuffling Horror will not drop any Ancestral Trinkets unless one of the trinkets is lost.