#Castle Scene Hazards — Fire Attack, Collapse, Smoke, and Barrier

Contents

Scene Tool. This document is an operating dictionary for turning the environmental hazards that pressure castle scenes (fire attack, rockfall, collapse, smoke, rain, night, and Barrier) into co existing gimmicks and zone modifications, with no new numbers. Every card follows the 02-01 conversion procedure and 02-02 structure cards, and does not redefine individual checks. Hazards are not a separate system; the issue is "which existing gimmick turns on under which trigger and pressure."

Number Boundary. This document does not create a new numerical system — every effect number uses the cited gimmick's value as written, and zone modification follows the formula in co-08-04. Damage is Wounds (not HP), time is rounds, and ranged shooting is Archery (covering bows and teppo; no separate gun skill). A Barrier being "destroyed by N attacks" is an explicit exception that quotes the attack-count convention in the co source text as written (not the introduction of a new HP number).

#Scent — What Brings Down a Castle

It is not the sword that brings down a castle.

Fire licks the watchtower, water soaks the ground underfoot, time dries the well, and darkness covers the eyes. Long before a sword crosses the castle wall, smoke erases the shooter's sight, fallen stones cut the road, and the shrine's Barrier binds the feet of yoma. Whether attacking the castle, defending it, or slipping inside, the first opponent is the environment.

#Law — Standard Hazard Card Format

All 7 cards follow 6 fields:

Hazard Name (Kanji)
├ What it pressures : 1~2 of sight, movement, supply, morale, time, spiritual
├ Matching co gimmick: existing co-05-05 / co-08-04 gimmick (quoted as written — link)
├ Trigger      : condition that turns it on (action declaration / lull d100 / GM discretion)
├ Clearing     : natural fade in rounds / check-based clearing / cause removed
└ GM Hook      : siege / defense / Infiltration / ruins — one line each

Do not create new gimmicks. A card only decides "which co gimmick is this hazard," and does not alter that gimmick's numbers. The only thing this document adds is a castle-scene application guide for triggers and stacking.

#Data — 7 Hazard Cards

#Fire Attack (火攻)

Fire Attack (火攻)
├ What it pressures : time · supply · morale
├ Matching co gimmick: fire zone(everyone 1 Wound each lull)
├ Trigger      : fire arrows·arson team / powder store destruction / lull event
├ Clearing     : natural fade after 2~3 rounds · rain/feng shui clears in 1 round
└ GM Hook      : 4 modes ↓

Gimmick Detail. fire zone — everyone in the zone takes 1 Wound each lull (friend or foe), barricades and buildings are automatically destroyed, and light armor or lower takes an additional 1 Wound. Setup uses fire attack (artisan/gaijin, 3 Energy) or a powder barrel consumable. Fire attack is impossible underwater or at the waterside (the underwater/waterside clause).
Burnout Candidates. Wooden watchtowers, warehouses (powder stores), and bamboo groves are candidates for "zone deletion" when set on fire (co-08-04 zone deletion) — a powder store is the castle version of a gunpowder supply depot explosion (everyone in the zone takes 2 Wounds).

Mode	GM Hook
siege	Burn the gate, watchtower, and warehouse to break the holdout from the inside — strike supply lines and morale at once.
defense	Fire attack immediately cuts both ways — while defending the castle, you cannot simply burn your own castle, so firefighting and feng shui matter.
Infiltration	A single spark (stolen powder or arson) disrupts a Blockade.
ruins	Remains of a burned place — a scorched fire zone lingers without fully cooling.

#Rockfall (落石)

Rockfall (落石)
├ What it pressures : movement · morale
├ Matching co gimmick: rockfall/collapse(Finesse ≥ 13 to avoid, on failure 2 Wounds + binding)
├ Trigger      : defender preparation action / battle noise / specific round
├ Clearing     : 1-shot trigger(fades after rolling down) · binding clears with Physique ≥ 15 or ally rescue 2 Energy
└ GM Hook      : 4 modes ↓

Gimmick Detail. rockfall/collapse — everyone in the zone avoids with Finesse ≥ 13; on failure, 2 Wounds + binding (buried). Escaping binding uses Physique ≥ 15 or ally rescue (2 Energy).
Active Defensive Rockfall. Rocks rolled by the defending side from a wall top, watchtower, or stonework are the co "area attack / roar trigger" repackaged as a defender preparation action (not a new check — a castle-scene application of existing trigger language). It is the move of the side holding high ground.

Mode	GM Hook
siege	Boulders rolling down a slope — deepen the pressure of the narrow path one more step.
defense	Rockfall from the wall top becomes an active weapon — hit the chokepoint with a preparation action.
Infiltration	A stealth route that circles around an unstable slope (read it ahead of time with Perception).
ruins	Stonework that collapses when touched — rockfall risk with every step.

#Collapse (崩壞)

Collapse (崩壞)
├ What it pressures : movement · time
├ Matching co gimmick: rockfall/collapse(chain·passage block) + zone modification(delete·block·merge)
├ Trigger      : tunnel·water attack / monsoon·ground / accumulated siege
├ Clearing     : irreversible(what collapsed does not return) · rubble passage uses Physique+Disable ≥ 13
└ GM Hook      : 4 modes ↓

Gimmick Detail. The "chain collapse (affects adjacent zones)" and "passage block (route movement impossible afterward)" variants of rockfall/collapse, plus co-08-04 zone modification. Reopening a collapsed rubble passage is Physique + Disable ≥ 13 (4 Energy, squad support -1).
GM Choice — What Does a Collapsed Wall Become?
Passage block — the road between two zones is blocked (cliff or rubble).
Zone deletion — that place itself disappears (watchtower collapse).
Zone merge — the castle wall falls, merging the Front Zone + Core Zone into one zone (co-08-04: post-merge cap = the smaller of the two caps + 1, base zones use 10 as the baseline). co-05-06 13 gap in a collapsed castle wall is the complete form (standard melee Core Zone).

Mode	GM Hook
siege	Bring down the wall with tunnels or water attack and open a gap (Core Zone) — break the wall instead of the main gate.
defense	The collapsed gap is the new battle line — a closed kuruwa suddenly becomes a melee Core Zone.
Infiltration	A gap in a fallen wall becomes a new road — a hole that was never in the agreement.
ruins	The essence of ruins — irreversibly collapsed structure is the maze.

#Smoke (煙)

Smoke (煙)
├ What it pressures : sight
├ Matching co gimmick: only the sight component of poisonous fog(ranged -2) — toxic damage off
├ Trigger      : side effect of fire attack / smoke screen / straw fire
├ Clearing     : wind(tengu·feng shui) · rain · natural fade in 1~2 rounds
└ GM Hook      : 4 modes ↓

Gimmick Detail. Smoke is a variation that turns on only the sight component of poisonous fog — sight -2 (Archery shots -2). It turns off the poisonous fog damage component of "each round, Physique ≥ 11 or 1 Wound" (apply full poisonous fog only for toxic smoke). The ranged shooting penalty applies to Archery (covering bows and teppo).
Clearing comes from wind (tengu or feng shui), rain, or environmental natural fade (co-08-04 1~2 rounds).

Mode	GM Hook
siege	Use smoke to erase the eyes of shooters on the wall and approach — force Archery -2.
defense	A reverse smoke screen, using straw-fire smoke to neutralize the attackers' shooting.
Infiltration	A gap where sight dies is a chance to hide — ride through the smoke.
ruins	Acrid smoke from embers that will not go out — sight is always hazy.

#Rain (雨)

Rain (雨)
├ What it pressures : movement (and turns off other hazards)
├ Matching co gimmick: no new gimmick — environmental modification(turns off fire attack and smoke)
├ Trigger      : weather / monsoon-season scenario / GM discretion
├ Clearing     : ends when it stops(rain itself is the environmental state)
└ GM Hook      : 4 modes ↓

Gimmick Detail. Rain does not turn on a new gimmick — instead, it is a hazard that turns off hazards. It clears a fire zone in 1 round (the co source says "rain/feng shui 1 round") and washes away smoke. Wet footing can make rockfall/collapse avoidance harder (GM discretion, no new numbers).
co gives no rule for its effect on teppo — do not invent a penalty such as weakened ignition in rain; describe it only at GM discretion if needed (without introducing numbers).

Mode	GM Hook
siege	Fire attack is blocked — a plan to break the castle with fire is broken by rain.
defense	Rainwater is an ally that extinguishes fire attack — though footing is slippery.
Infiltration	Rain sound covers footsteps — an ally to stealthy movement (narrative advantage).
ruins	Structure soaked by rain and easier to collapse — background for a collapse trigger.

#Night (夜)

Night (夜 / darkness)
├ What it pressures : sight
├ Matching co gimmick: night weather(all checks -2·Infiltration +3) / simple darkness(Infiltration +2·Archery -2)
├ Trigger      : night attack declaration / scene time / broken lantern
├ Clearing     : torch·moonlight(partial clearing) · daybreak
└ GM Hook      : 4 modes ↓

Gimmick Detail. Night uses the weather rules from co-03-09 as written — all checks -2 (exception for being near a light), Infiltration +3, and yoma encounter chance 2 times. Simple darkness (inside a ruined castle, a broken lantern, or a room light does not reach) is treated as a sight-blocking state, borrowing Infiltration +2 · ranged (Archery) -2 from forest/brush, or Infiltration +2 from narrow interior. Torches and moonlight partially clear it.
Two-sidedness. Night and darkness are an advantageous environment for Infiltration mode = a disadvantageous environment for defense mode — a shadow to the one entering, a blind spot to the one guarding.

Mode	GM Hook
siege	Aim at blind spots with a night attack — but allied shooting (Archery) is also -2.
defense	Darkness is a blind spot — fill it with torches, but light immediately becomes a target.
Infiltration	The sharpest environment — night gives Infiltration +3, simple darkness gives Infiltration +2. The gap in a guard shift.
ruins	Inside a ruined castle where no light enters — darkness is a constant environment.

#Barrier (結界)

Barrier (結界)
├ What it pressures : spiritual (movement block · morale)
├ Matching co gimmick: Barrier(yoma entry 2 Wounds or Wisdom ≥ 11)
├ Trigger      : constant Barrier at shrine·wayside shrine / caster setup(2 Energy)
├ Clearing     : destruction(yoma attacks 3 times·great yoma 1 time) · Exorcism Wisdom+Exorcism ≥ 15 · natural fade in 3 rounds
└ GM Hook      : 4 modes ↓

Gimmick Detail. Barrier — on yoma entry, 2 Wounds or entry check (Wisdom ≥ 11); allies inside the Barrier are immune to Fear and negate Spiritual Taint. Setup uses 2 Energy from a character with the Barrier skill, with upkeep of 1 Energy/lull. Destruction takes yoma attacks 3 times, a great yoma 1 time, or natural fade after 3 rounds. The Exorcism destruction check for a spiritual Barrier is from co-08-04: Wisdom + Exorcism ≥ 15.
A castle Barrier at a shrine or wayside shrine is both a defense resource (the last spiritual wall of a closed castle) and an obstacle for Infiltration and ruins (a spiritual blockade line). The spiritual effect is an assumed setting in this volume and is self-contained with co gimmicks alone (not dependent on ex/fc08).

Mode	GM Hook
siege	If you brought yoma forces, the Barrier must be broken first before entry is possible — target the caster or ritual implement.
defense	The Barrier is the last line holding back yoma — someone must afford the upkeep (1 Energy/lull).
Infiltration	A blockade line of sacred ground — yoma companions cannot cross, and humans carry the taboo.
ruins	A broken Barrier site is the epicenter of Spiritual Taint — a shadow gate with its seal undone.

#Procedure — Trigger, Stacking, and Clearing

#Three Routes That Turn on Triggers

Action declaration — the siege or defense side actively sets up fire attack, rockfall, tunnels, and so on.
Lull event — use d100 if pure probability is needed, and d10 for an improvised single gimmick (the castle version of co-05-05 d10 random gimmicks — citation and compression, not a new table). Zone modification is declared at the lull step or a specific trigger (co-08-04).
GM discretion — scenario milestones (water attack complete, daybreak, tunnel breakthrough).

The time unit is rounds, recovery notation is Wounds recovery, and the check formula is 2d10 + attribute + skill ≥ Target Number. Hazards do not bring in a new die.

#Stacking Rules (`co-08-04`)

A single zone can have at most 3 types of simultaneous environmental effects. If exceeded, the GM declares the oldest one faded.
Same type uses only the highest value (fire twice = once), while different types all apply.

Common castle-scene combinations:

Combination	Effect
Fire attack + smoke	1 Wound each lull (fire) + Archery -2 (smoke sight) — atop a burning castle wall
Smoke + simple darkness	Archery -2 does not stack; only the highest value -2 applies (same sight type) — Infiltration +2 remains
Barrier + Spiritual Taint	Inside the Barrier, Spiritual Taint is negated (offset) — the Barrier turns off the taint
Collapse + fire attack	Collapsed gap (Core Zone) + fire zone — the sharpest final phase of a siege

#Three Routes of Clearing (`co-08-04`)

Natural fade — fire attack 2~3 rounds, smoke 1~2 rounds, Barrier 3 rounds. Time turns them off.
Check-based clearing — physical rubble (Physique + Disable ≥ 13), spiritual Barrier (Wisdom + Exorcism ≥ 15), environment (feng shui master [twist leyline], Pure Land monk [great dharma assembly], rain, wind).
Cause removed — defeat the arson team, defeat the caster, cut off the powder store.

Hazards are part of the economy that reuses one castle four times. The same fire attack is a weapon in siege, double-edged in defense, disruption in Infiltration, and residue in ruins — the 4-mode GM hooks in §Data are those four faces.

"Before a sword crosses the castle wall, fire, water, and darkness decide the castle's fate first."