The antitheist wolf who leads the Free Pack, the major Ewefall boss and the one boss the Lamb can never recruit.
Marchosias is the one boss in Cult of the Lamb who will never kneel. Every other defeated leader can be dragged home and indoctrinated, but the wolf at the top of Ewefall hates gods and cults so completely that the developers have said he will stay unrecruitable on purpose.
He is the patriarch of the Free Pack and the major boss of the Ewefall biome added in the Woolhaven DLC. Per the wiki, the Lamb is sent to remove him and his pack from the mountain on behalf of Rotted Yngya.
His whole fight is wrapped in the Rot. According to the wiki he confronts the Lamb over the rot spreading across his mountain, demanding either all of your Rotburn or the destruction of the Rotten Followers you keep, before the final showdown in the Fallen Temple.
This guide covers who Marchosias is, his place in Ewefall and the Woolhaven story, his three boss phases, why he can never become a follower, and how he compares to the recruitable mini-bosses of the base game.
A gray wolf boss with three escalating phases, fought at the top of Ewefall.
Ewefall, the mountain biome added in the Woolhaven DLC, ending at the Fallen Temple.
He cannot be recruited. As an antitheist, he is the only boss the Lamb can never turn into a follower.
Leader of the Free Pack, sent against the Lamb to stop the Rot on his mountain.Marchosias is a gray wolf and the leader of the Free Pack. Per the wiki he has four cyan eyes with black sclera, a stitched hole in his forehead, and a purple cloak covered in the symbols found throughout Ewefall, with a Charged Shard chained to his spiked collar.
He is an antitheist at his core. According to the wiki he hates gods, faith, cults, and religion itself, and he hates the 
Bishops for how they treated him and his future Packmates. He freed that pack through science, using the Defiler of the Divine.
His names tell the story others give him. The wiki lists his aliases as The Heathen Marchosias, the Big Wolf, the Wretched Wolf, and the self-titled Liberation. Like the base-game mini-bosses, his name comes from the Ars Goetia, the demon hierarchy of the Lesser Key of Solomon.
Marchosias is the major boss of Ewefall, the mountain biome added in the Woolhaven DLC. Per the wiki, the Lamb climbs his mountain on behalf of Rotted Yngya to drive him and the Free Pack out, and he dies in the Fallen Temple at the summit.
The Rot drives the whole conflict. According to the wiki, Marchosias sees the rot spreading across his mountain as filth that sickens him and the pack, and across his encounters he demands the Lamb hand over every Rotburn or destroy the Rotten Followers in the cult. He believes he can use the Rotburn to find a cure.
The road to him runs through a sub-boss. The wiki lists an Abas boss fight in Ewefall before the encounters with Marchosias build toward the Final Encounter, so he is the climax of the Ewefall crusade rather than a quick mini-boss like the early base-game fights.
Marchosias escalates through three boss phases. Per the wiki his combat forms are listed as Boss, 
Boss Phase II, and 
Boss Phase III, each a more dangerous version of the wolf than the last.
His design hints at how the fight ramps. The wiki describes the Charged Shard on his collar and the Defiler of the Divine he wields, and his later phases push him further from the wounded patriarch of the opening into a faster, more aggressive threat as his health drops.
The wiki does not yet have his full health values or a complete attack-by-attack breakdown filled in, which is common for recent DLC bosses. We are flagging that gap rather than guessing numbers; the verified structure is the three escalating phases ending in the Fallen Temple.
Treat each phase as a fresh read. Because Marchosias adds pressure with every phase rather than swapping to a single desperate mode, the safe approach is to learn his openers in phase one, then expect the same tells to come out faster in phases two and three rather than brand-new attacks.
Beat Marchosias by playing the long game and respecting his three phases. He is the climax of the Ewefall crusade, so bring your strongest crusade loadout and plan for a fight that escalates rather than ends quickly.
Your best crusade weapon (a three-phase wolf is a damage check, so bring reliable output) A dependable ranged Curse (chip him when he repositions on the mountain) Survive the ramp (each phase is faster, so prioritize dodging over greed) Clear the Rot first (handle his Rotburn demands and Ewefall before the final fight)The encounters before the fight matter. Per the wiki, Marchosias gives the Lamb choices about the Rotburn and the Rotten Followers across multiple meetings, so the final boss is the payoff of the Ewefall questline, not a standalone arena you can rush blind.
Patience carries it. In practice, the players who struggle are the ones who play the first phase like a quick mini-boss; the wolf rewards steady, low-risk damage through all three phases far more than an early all-in.
Marchosias is the only boss the Lamb cannot turn into a follower. Per the wiki, the developers have said the game will not be updated to make him recruitable because it goes too far against his character as an antitheist who despises cults.
That makes him the opposite of the base-game mini-bosses. 
Leshy's Darkwood lieutenants, Amdusias, Valefar, and Barbatos, all surrender and join the cult once defeated. Marchosias never does.
It fits a wolf who freed his own pack from the gods. Recruiting him would mean folding him into exactly the kind of religious worship he spent the whole DLC fighting, so his permanent refusal is the most consistent thing about him. For the full roster, see every Cult of the Lamb boss in one place.
Marchosias is the wolf at the top of the Woolhaven DLC. These guides cover the expansion, the crusade tools, and the rest of the roster.
Game data and screenshots adapted from cult-of-the-lamb.fandom.com, used under CC BY-SA 3.0. Original content remains the property of the wiki contributors and Massive Monster and Devolver Digital.