Overview
Beyonder Monsters (失控者 / 怪物) are Beyonders who have lost control of their Pathway and transformed into supernatural creatures. They are one of the principal enemy types the player encounters in Lord of Mysteries. Many anomaly investigations resolve into a Beyonder Monster confrontation; many dungeon bosses are Beyonder Monsters at high Sequence.
How a Beyonder loses control
Loss of control is the source-material framing the game adapts. The higher a Beyonder's Sequence, the greater their inhuman inclinations relative to their original humanity, and the higher the risk of falling into one of three deteriorating stages:
Warning signs: auditory and visual hallucinations. The Beyonder is still in control but has lost some certainty about which perceptions are real.
Body and mind out of control: terrifying or strange states surface intermittently. The Beyonder's behaviour becomes erratic and predatory.
Complete breakdown: the Beyonder transforms fully into a Beyonder Monster. The original person is gone; what remains is a hostile creature shaped by the corrupted Pathway.
Drinking a Beyonder potion without sufficient Acting Method preparation, repeated low-sanity exposures, and witnessing high-Sequence rituals without protection are the major triggers. See the Sanity System page for the full madness-state ladder that culminates in monster transformation.
Player-character risk
The player's own Beyonder character can transform into a Beyonder Monster under specific story-locked failure conditions. The transformation is not a permadeath; it is a recoverable corruption state that requires a high-cost story-locked ritual to reverse. The affected character carries a visible scar of the event for the rest of the playthrough.
Mr. Fool's grafting does not protect the player from monster transformation. The grafted abilities are kit-defining, not safety guarantees; failed potion ceremonies can still corrupt a player character.
As enemies
Beyonder Monsters appear as combat enemies across the campaign:
Solo creature enemies: low-Sequence Beyonder Monsters surface in field zones and small dungeons.
Boss-tier creatures: mid-Sequence Beyonder Monsters serve as dungeon bosses.
Setpiece encounters: high-Sequence Beyonder Monsters appear in the campaign's apex moments. The Tingen-arc finale (the source-material's Tingen City Doomsday event) is one such encounter; players witness or participate alongside Dunn Smith and the Nighthawks in the canonical sacrifice that resolves it.
Pathway-themed monsters
Each Pathway produces distinct monster forms. A failed Seer becomes a divinatory horror with reality-distortion abilities; a failed Apprentice becomes a mobility-and-chaos creature; a failed Spectator becomes a mind-domination creature; a failed Warrior becomes an unstoppable physical menace; a failed Bard becomes a song-warped predator; a failed Mystery Pryer becomes a knowledge-cursed entity that drives investigators mad with secrets they cannot un-know.
Beyonder Monsters often retain partial memory of their pre-transformation life. The Tingen Nighthawks treat this as a moral consideration: a recently-transformed monster may sometimes be stabilised before completing the breakdown, which produces some of the campaign's most ambiguous side-quest decisions.
Mythical Creature Forms
Above the basic Beyonder Monster level, advanced Beyonders can take on Mythical Creature Forms specific to their Pathway. Sequences 4 and 3 develop incomplete Mythical Creature Forms; Sequences 2 and 1 develop complete ones. These appear in late-game story content and apex-tier raid encounters; the Crimson Test does not surface this content.