You have inherited a shelf, not a census. Every file in this project — every modification, spell, monster, piece of iron, race, and floor — is an entry on a shelf the Saint is free to reach past at any moment. Your job as builder is not to fill the shelf until it is complete. It is to keep the shelf honest: each new thing a true addition, never a contradiction, and always one the pit could have made.
The single law everything hangs on
Numbers are flat, and nothing multiplies except the die. There are no damage dice, no dice of any kind for damage or healing anywhere. A printed number is the number. The d20 is where uncertainty lives, and it runs the whole machine: the natural 18 doubles, and that is the only doubling the game trusts. A modification adds once, after every multiplier, and is never itself doubled, scaled, or halved. This is not a stylistic preference; it is the spine of the economy. Every weapon, modification, spell, and monster you build is a new line in that arithmetic, and the arithmetic never bends for the entry.
Before you write anything, feel the whole of the law — read the Pit Master's Guide once, slow. The rest of this book is that law, taken one file at a time, arranged as the builder uses it.
Closed shelves you never add to
Some lists are closed by design because the game's decisions live inside them, not in their number. Do not re-open them:
- The four stats. Strength, Dexterity, Arcane, Wisdom.
- The eleven elements. Fire, Water, Earth, Air, Lightning, Frost, Acid, Rot, Blood, Shadow, Sun — in five origins. An element names mechanics that already exist; it never adds one.
- The nine spell types and eight styles. A spell is one type × one style. The taxonomy is the vocabulary, closed.
- The mission styles and the medieval eras. Both are closed lists. You invent the floor, never a new shelf.
- The six rarity rungs and six modification families. New rungs, no. New families, no.
These are the boundaries that make the open parts safe to build in. Spend your invention where the pit intended it: the flesh of new entries inside the existing grammar.
The skills are open where names close. The skill list is five, and closed — acrobatics, stealth, awareness, medical, survival. Within them the builder is free; a skill is a name and a ladder, and the pit prices the work, not the label. The one law that never opens: talking is not a die. What a character says, the Saint hears — the argument is the roll, and the Saint's ear decides.
The three tests of a good entry
Ask three questions before you write a file, and write a file only if all three pass:
- Does it speak the existing vocabulary? A new modification uses flats, bleed, dodge, catch, wide, thresholds, leech, reach — the tools already on the shelf. A new skill uses a name already on the shelf. It never invents a new percentage, a new die, or a new save. No dexterity-of-the-mind, no poison-save, no crit-range.
- Does it obey the ceilings? Bleed caps at 3. Dodge never falls below 0, and external penalties stack to a maximum of −2. Armor never exceeds a DC of 17. A two-handed weapon gains 2 slots over its rarity and caps at 8; a small one-hander caps at 3. Keep every number inside these fences.
- Is it the pit's? Does it read like something the pit made, or like a rulebook bolted on from outside? A modification with a name like Poison Resistance is a bolt; Winter's Law is the pit. The tone is part of the mechanism — it tells the table how to hold the thing.
Where the builder and the player part
The Player's Handbook says how the rules work at the table. This book says how to add to the rules without breaking them, and what the builder was trying to do. If a rule is needed both to play and to extend, it lives in the Player's Handbook, and this book only says how to extend it. Do not paste a rule twice.
What follows walks the archive shelf by shelf — iron, spells, monsters, floors, and the people of the Rim — then closes on how to remake the whole thing as your own.
