The Breath-Chain Below the Cathedral
This ancient ward is both shield and furnace. It keeps the volcanic vent beneath the Cathedral of the Sacred Breath dormant, while drawing its heat upward through hidden channels to warm the nave, cloisters, and dormitories. So long as the lattice remains intact, the building is comfortable and the vent sleeps. If the seals fail, the ward will no longer bleed off pressure. The foundations will blacken, the stone will split, and the cathedral may become the mouth of a catastrophic eruption.
The Breath-Chain Below the Cathedral
Defenses
Detection
“A ring of black basalt and silver inlay sits buried beneath the cathedral floor, hidden behind the altar stones and old heat vents. Faint gold script crawls through the seams like glowing breath, and the tiles above it are always warm, even in winter. When the ward stirs, runes flicker red-orange beneath the stone, as if a furnace is dreaming under the church.”
Standard Engagement
The ward activates when anyone disturbs the foundation seal, tampers with the altar stones, breaks a conduit rune, or allows the heat balance to drift beyond its tolerances.
On initiative 20, the ward sends heat through the foundations and releases one pulse. If no one is actively working to disable it, the pulse intensifies the chamber's temperature, dealing its damage and advancing instability by 1 if any seal has already been broken. If the ward is partially disrupted, it lashes out at the nearest creature touching stone or metal within the hazard area, favoring those who tamper with the seams or pillars.
The ward reattunes itself at dawn if instability is 0 and no disabled conduit remains exposed. If instability is 1 or 2, it remains active but unstable until repaired. If the hazard is fully disabled, it can only be restored by a long ritual in the presence of the cathedral's high clergy or a powerful arcanist.
Each round on initiative 20, the ward pulses. Every creature in the hazard area must make a DC 15 Dexterity saving throw. On a failure, the creature takes 2d6 fire damage and 1d6 thunder damage as a burst of superheated air and stone shards erupts from the seams. On a success, the creature takes half damage.
If at least one check to disable the hazard has failed since the last pulse, the pulse also fills the area with choking ash. Creatures that failed the save are blinded until the start of their next turn, and creatures that can breathe must succeed on a DC 13 Constitution saving throw or be unable to take reactions until then.
If instability reaches 3, the ward loses control. Each creature in the hazard area must make a DC 15 Dexterity saving throw, taking 4d6 fire damage and 2d6 bludgeoning damage on a failure, or half as much on a success. In addition, one 10-foot section of floor in the area collapses into a vent fissure, becoming difficult terrain until repaired.
The hazard occupies a 20-foot radius area around the foundation seal. Creatures standing on the stone floor in the area count as being in the hazard area for its effects.
Whenever a creature fails a disable check, the ward gains 1 instability. At 3 instability, the next pulse becomes a vent surge and the instability resets to 0 only after the area is fully stabilized.
Creatures that spend an action praying, chanting the cathedral's old litany, or presenting a sacred symbol can grant advantage to the next check made by themselves or an ally to disable the hazard, provided the creature succeeds on a DC 12 Wisdom (Religion) check.
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