Powerful magic, supernatural disasters, the influence of potent monsters, or the whim of a demigod can cause the boundaries between the Material Plane and an Elemental Planes to wear thin, resulting in an elemental influx that transforms normal wildlands into a dangerous region. Often, creatures such as dragons or other monsters with energy resistances or immunities seek out regions of elemental influx as their domains, and such a creature’s presence can enhance or expand an existing influx.
The following list describes only some of the types of effects an elemental influx might have on the landscape. GMs are encouraged to expand on this list as they see fit.
Acidic Miasma (CR 3): An acidic miasma wafts up from the waters of a swamp infused with toxins leaching in from the Plane of Earth. Exposure to low concentrations of the foul vapors in the swamp causes a mildly uncomfortable burning sensation on exposed skin. Higher concentrations of the miasma are more deadly, usually appearing in pockets 1d6+1 x 10 feet in radius. Upon entering the area of a highly concentrated acidic miasma, a creature must immediately succeed at a DC 15 Fortitude save or become sickened for 1d4 minutes. Creatures that fail the save by 5 or more become nauseated instead. These effects last even if the creature leaves the area of the miasma. Additionally, each round a creature starts its turn in a highly concentrated area of miasma, it takes 1d6 points of acid damage. Highly concentrated miasmas can be identified from 10 feet away by their distinctive stench with a successful a DC 20 Knowledge (nature) or Survival check.
Acidic Plants (CR 3): Acidic plants—usually bushes, mosses, vines, and other undergrowth—are found in clusters with a radius of 1d6+1 x 10 feet. They become active when they are disturbed by creatures moving through their squares. Acidic plants gain a reflexive ability to grab at intruders, and they attempt to grapple creatures moving through their square. The plants have a CMB of +10, and their grapple attempts do not provoke attacks of opportunity. Creatures grappled by acidic plants take 1d6 points of acid damage each round and can’t move without first breaking the grapple (the acidic plants’ CMD is 20). The acidic plants receive a +5 bonus on grapple combat maneuver checks against opponents they are already grappling, but they can’t move or pin foes. Each round that acidic plants succeed at their grapple combat maneuver check, they deal an additional 1d6 points of acid damage. A cluster of acidic plants has AC 10 and 10 hit points. Acidic plants have acid immunity and vulnerability to cold. Burning a square of acid plants causes them to release an acidic gas that spreads in a 10-foot radius; any creature in this gas takes 1d4 points of acid damage. The cloud dissipates in 2d4 rounds unless dispersed earlier by a strong wind or a gust of wind spell. Acidic plants secrete a nearly transparent layer of acid that can be identified with a successful DC 20 Knowledge (nature) or Survival check.
Electrified Duststorm (CR 5): An electrified duststorm begins suddenly, scouring the area in a fierce but short-lived storm lasting 1d6+1 rounds. In addition to the effects of a duststorm, arcs of electricity crackle throughout it. Each round a creature is caught in the storm, it must succeed at a DC 15 Reflex save or take 2d6 points of electricity damage. The onslaught of an electrified duststorm is presaged by a sudden crackle of harmless sparks across the ground 1 minute before it starts and can be identified with a successful DC 20 Knowledge (nature) or Survival check.
Fire Storm (CR 5): Occurring in mountainous areas, fire storms rage with strong winds, raining ash and flame across the landscape. A fire storm usually forms somewhere near a mountain peak and travels downward, but it persists for only 1d6+1 rounds. A creature caught in a fire storm takes 2d6 points of fire damage per round and must succeed at a DC 15 Reflex save or any flammable items that it has catch on fire. Additionally, the ash mixed in with the fire makes the ground difficult terrain and reduces visibility by half, imposing a –6 penalty on Perception checks. Fire storms move quickly, at a rate of 60 feet per round, and have a radius of 1d4x100 feet. A fire storm can be identified as it begins forming over the course of 1d4+1 rounds with a successful DC 20 Knowledge (nature) or Survival check to detect the telltale increase in heat and gently falling ash.
Freezing Eruption (CR 5): Freezing gouts of super-chilled air erupt from small vents in the ground, blasting a 5-foot square with subzero temperatures. A creature occupying the square must succeed at a DC 15 Reflex save to avoid the freezing eruption. On a failed save, the creature takes 2d6 points of cold damage and becomes entangled, as it is encrusted with ice. A creature can break free from the encrusting ice with a successful DC 20 Escape Artist or Strength check, but it takes 1d4 points of cold damage at the start of each turn it remains encrusted. The encrusting ice melts away in 1d6 rounds in regions where the ambient temperature is above freezing. Freezing eruptions occur from the same vent every 1d4 minutes. A square containing a freezing eruption can be identified by the shards of ice around it with a successful DC 20 Knowledge (nature) or Survival check.
Pathfinder Roleplaying Game: Ultimate Wilderness © 2017, Paizo Inc.; Authors: Alexander Augunas, John Bennett, Robert Brookes, John Compton, Dan Dillon, Steven T. Helt, Thurston Hillman, Eric Hindley, Mikko Kallio, Jason Keeley, Isabelle Lee, Jason Nelson, Stephen Radney-MacFarland, Alex Riggs, David N. Ross, David Schwartz, Mark Seifter, Jeffery Swank, and Linda Zayas-Palmer.