Ironrot Lichen

This reddish lichen is difficult to see on the pile of rusted metal where it grows.

Ironrot Lichen CR 7

XP 3,200
N Small plant
Init +5; Senses low-light vision, tremorsense 60 ft.; Perception +8


AC 20, touch 16, flat-footed 15 (+5 Dex, +4 natural, +1 size)
hp 85 (10d8+40)
Fort +11; Ref +8; Will +3; Immune cold, electricity, plant traits


Speed 10 ft., climb 10 ft.
Melee tentacle +6 touch (3d6 acid and rust)
Space 5 ft.; Reach 5 ft. (10 ft. with tentacle)
Special Attacks ironrot plague, spore cloud


Str 6, Dex 21, Con 18, Int -, Wis 11, Cha 5
Base Atk +7; CMB +4; CMD 19 (can’t be tripped)
Skills Climb +6, Perception +8; Racial Modifiers +8 Perception
SQ camouflage


Camouflage (Ex)

An ironrot lichen looks like normal rust and corrosion on a metal surface when at rest. A creature must succeed at a DC 22 Knowledge (nature) or Survival check to notice it before it attacks for the first time.

Ironrot Plague (Ex)

Spore cloud-contact; save Fort DC 19; onset 1 day; effect 1d4 Con damage to living creatures, 1/4 of maximum hp to metal objects; a creature that dies or an object destroyed as a result sprouts a new patch of ironrot lichen in 1 hour; cure 2 consecutive saves. Only metal creatures and magic objects receive a Fortitude save against this disease, other metal objects automatically fail. If an infected metal object touches another metal object, it has a 25% chance of transferring the disease.

The save DC is Constitution-based.

Rust (Ex)

The touch of an ironrot lichen’s caustic tendril corrodes metal, causing a metal object as large as a 5-foot square and one inch thick to take half of its maximum hp in damage and gain the broken condition (DC 19 Reflex negates for an attended or magical object). A second failed save destroys the item. Against creatures made of metal, a ironrot lichen’s tendril deals double damage (DC 19 Reflex half); this damage ignores damage reduction and hardness. The save DCs are Constitution-based.

Spore Cloud (Ex)

Once every 1d4+1 rounds, an ironrot lichen can release a 10-foot-radius cloud of spores as a standard action.

Creatures and objects within the cloud must save or contract ironrot plague.


Environment any non-aquatic
Organization solitary, pair, or carpet (3-8)
Treasure none

Ironrot lichens faced extermination in most inhabited areas after infestations of the plant wiped out armor, tools, and weapons, while spreading from settlement to settlement on tainted metal. The hardy plants went into a long dormancy in hidden areas, and have thus far avoided complete destruction. Ironrot lichens can enter a long-term stasis, and they reawaken after many locations have forgotten about the massive damage they cause. They also thrive in extreme environments where they could reproduce through red-blooded creatures populating those environments. Patches of dormant ironrot lichen have also spread to airless locations in space, becoming a menace to miners who rely on metal tools and habitats on the asteroids they work. A patch of lichen takes up a roughly 3-foot-diameter space and is virtually weightless.

Rumored to be a creation of the Hegemony, ironrot lichens sprouted simultaneously on many worlds where they unleashed considerable devastation. The first ironrot lichens only corroded metal and spread slowly enough to allow infested metal to easily come into contact with other metal objects.

Whether through deliberate or unintentional mutation, ironrot lichens metamorphosed such that they inflict caustic wounds to flesh, and their destruction of iron also extended to iron contained in a living creature’s blood. The lichens are immune to temperature extremes and even magical sources of cold, but fire destroys it. Unfortunately, using fire also causes the lichens to release spores which escape the fire and drift away on the wind. Druidic sects of a particularly malevolent bent gather and cultivate ironrot lichens and use them in their attempts to undermine large population centers. In areas where mining claims are contested, one group may resort to using ironrot lichens as instruments of sabotage.

Section 15: Copyright Notice

Legendary Planet Adventure Path © 2019, Legendary Games; Authors: Authors: Matt Goodall, Jim Groves, Steven T. Helt, Tim Hitchcock, Jason Nelson, Richard Pett, Tom Phillips, Mike Shel, Neil Spicer, Mike D. Welham.

scroll to top