Lethean Age Monster Handbook

The Monster Handbook explains the creatures of the Lethean Age: what they are, how they are classified, how they behave in the world, and how to use them at the table. It should teach ecology and encounter use alongside stat blocks.

This file intentionally starts as a table of contents and migration map. No existing canon has been moved into it yet.

How To Use This Book

Use this handbook when you need to understand, run, build, or adapt creatures. Use the regulations for exact generation, serialization, and deterministic resolution procedures.

Part 1: What Monsters Are

Draft sections:

• Adaptation, not design.
• Creatures of place.
• The miasma as ecology.
• Creatures are wildlife, not pets.
• Sapient creatures are people, even when alien.

Part 2: Creature Types

Draft sections:

• Humanoids.
• Beasts.
• Constructs.
• Plants and myconoids.
• Phantasms.
• Monstrosities.
• Oozes.
• Why giants are not a creature type.

Part 3: Creature Statistics

Draft sections:

• Ability scores.
• Size.
• Hit points.
• Action points.
• Armor Class.
• Traits.
• Levels and danger.

Part 4: Mutations And Lineages

Draft sections:

• Administered mutations.
• Traumatic mutations.
• Parasitic mutations.
• Lattice nodes.
• Base pairs.
• Core pairs.
• Omega pairs.
• Vril pairs.
• Upvolving traditions.

Part 5: Building Encounters

Draft sections:

• Biome-driven encounters.
• Miasma-driven powers.
• Environmental pressure.
• Stronghold actions.
• Morlock, Eloi, Beastfolk, Rur, Android, and Cyborg encounter framing.
• Redoubt-adjacent encounters.

Part 6: Monster Entries

Beast

• Ashbear (CR 1)
• Ashbeetle (CR 0)
• Bladefin (CR 1/2)
• Constriction-Snake (CR 1/4)
• Deepfin (CR 3)
• Driftlens (CR 1)
• Galloper (CR 1/4)
• Glaive-Tail (CR 3)
• Grapple-Toad (CR 1/4)
• Gulper (CR 1)
• Gutmaw (CR 5)
• Hookbeak (CR 0, CR 1/8)
• Ironback (CR 1/4)
• Pack-Viper (CR 1/8, CR 1/2)
• Ridgeback (CR 1)
• Scrabble-Pack (CR 1/4)
• Siltjaw (CR 1/2)
• Sprintfang (CR 1/4)
• Strikewing (CR 1)
• Tallhorn (CR 2)
• Tidecrab (CR 1/8)
• Vaultstalker (CR 1)

Humanoid

• Hookclaw Warders (Scout CR 1, Stalker CR 3)
• Lockstep Warders (Warder CR 1/2, Commander CR 3)
• Resonance Keeper (Novice CR 1/4, Keeper CR 2)
• Shoreborn Skirmisher (CR 1/8)
• Signal Adherent (Follower CR 1/8, Adherent CR 2)
• Surface Humanity (Settler CR 0, Waykeeper CR 3)
• Warrener (Scout CR 1/8, Warder CR 1/4)

Ooze, Plant, Construct, Phantasm, and Monstrosity entries are planned but not yet drafted.

Review Notes

• Avoid turning sapient peoples into generic monsters.
• Keep creature danger ecological rather than moral.
• Omega-pair creatures can be unique without implying supernatural origin.
• "Undead" style creatures should be explained as substrate-resident or nanite-maintained phenomena, not souls or curses.