Natural disasters go far beyond environmental hazards, leaving death and devastation in their wake. Supernatural disasters can be even more disruptive, with the potential to permanently scar the world. A disaster is more like an adventure than a single encounter — it has no single CR. Each phase or hazard within the disaster should be treated as a separate encounter with a CR appropriate to the party.

Some disasters happen in moments (earthquakes, tsunamis); others unfold in escalating stages over days or weeks (volcanoes, undead uprisings). Adjust pacing to fit your campaign's needs.

Volcanoes

Volcanic eruptions offer a range of distinct hazards. GMs may also precede a major eruption with avalanches and minor earthquakes. The four primary volcanic hazards are:

Lava Flows no fixed CR
Speed (typical)
15 ft./round
Speed (hot flow)
up to 60 ft./round
Speed (lava tube)
120 ft./round CR 6
Engulf save
DC 20 Reflex or engulfed (success = contact only)

On a failed save the creature is immersed in lava; on a success it is in contact but not engulfed. Apply lava damage rules from the damage & healing rules (fire damage per round while in contact or immersed).

Lava Bombs CR 2 CR 5 (large)
Blast radius
30 ft.
Damage (normal)
4d6 — DC 15 Reflex for half
Damage (large)
12d6 — DC 15 Reflex for half
Cover bonus
+2 to save (shield or hard cover)

Molten rock hurled several miles from the eruption cools to solid rock before landing. The GM designates the impact point.

Poisonous Gas CR 5
Damage
1d6 Con/round (inhaled)
Fort save
DC 15 negates; DC +1 per prior save
Cloud height
typically 50 ft.

Toxic vapors often go unnoticed amid fire and destruction. Visible gases also function as heavy smoke. Clouds flow to low ground; gale-force winds or high barriers can divert them (if the gas has somewhere else to go).

Pyroclastic Flows CR 10
Speed
500 ft./round (avalanche speed)
Contact damage
2d6 fire/round
Buried damage
10d6/round
Gas effect
Poisonous gas (see above)

A crushing wave of burning ash, hot gases, and volcanic debris. Only miracle or wish can turn aside or impede a pyroclastic flow.

Tsunamis

Tsunamis (tidal waves) are crushing walls of water triggered by underwater earthquakes, volcanic blasts, landslides, or asteroid impacts. They are nearly undetectable at sea — the wave builds only as it nears shallow water. Depending on wave size and coastal slope, floodwaters can travel hundreds of yards to over a mile inland, then drain back, dragging debris and creatures out to sea.

Structural Damage
  • Temporary and poorly built structures — obliterated or displaced
  • Well-built structures — ~25% destroyed; survivors take significant damage
  • Serious fortifications — lightly damaged
  • ~25% of the area's population perishes (swept out to sea, drowned, or buried)
Creature Effects
Swept out to sea
DC 25 Swim or pulled 6d6 × 10 ft. offshore
Collapsing building
6d6 damage (DC 15 Reflex half); 50% chance of being buried
Post-tsunami water
Always rough or stormy (barring magic)

Undead Uprising

Whether caused by an ancient curse or fell necromancy, an undead uprising strikes wherever the dead have been laid to rest — not just cities, but blood-soaked battlefields and forgotten graveyards. The disaster unfolds in escalating waves across days or weeks, with daytime offering brief reprieves as daylight suppresses the undead's power.

Stage 1 The Unquiet Dead

The recently buried rise as zombies. Bodies in consecrated ground remain at rest, but those in mass graves or left unburied shamble into the streets. Only a few break free at first; numbers grow each night.

At dawn, the dead seek shelter in graves or hidden places. Those caught in daylight flail about confused until destroyed or able to stagger into cover. Non-humanoid corpses may begin to rise at the GM's discretion.

Stage 2 Skeletal Awakening

Older corpses join the horde — ancient skeletons claw from graveyards and crypts, organized by the uprising's magical power into something resembling a living army. They scavenge weapons, armor, and magic items from abandoned graves.

Skeletal champions lead the troops. Ghouls and wights prowl the streets after dark, along with other lesser free-willed undead.

Stage 3 Lost Souls

Souls long since turned to dust awaken as ghosts, shadows, wraiths, and spectres. A handful of ghosts may be free from the uprising's influence and able to provide the PCs with intelligence.

Negative energy suffuses the area, granting all undead the benefits of desecrate. Formerly consecrated ground reverts to normal; only hallowed ground remains inviolate.

Colors grow muted and gray except at brightest midday. Even light-sensitive undead can move freely from late afternoon to mid-morning.

Stage 4 Necropolis

If the negative energy flow is not reversed, darkness claims the area permanently. The entire zone functions as unhallow (no bonus spell attached). The last hallowed sanctuaries fall. Heroes who died fighting the uprising return as fearsome undead generals.

Survivors are enslaved as thralls. Free-willed undead flock to this new sanctuary. Only the mightiest heroes can reclaim the blighted area for the living.

GM tip: The undead uprising pairs naturally with haunts (unquiet spirits tied to specific locations) and the encounter budget rules to calibrate nightly wave CRs to the party's level.