The following is a draft 3.5e conversion of the carapace monster from Wolfgang Baur’s article “The Dragon’s Bestiary: Monsters of the Underdark” from Dragon 227.

A fungal carapace is an aggressive form of Underdark fungus, a symbiont that can adapt itself to living on almost any vertebrate creature, from reptiles to mammals to fish. It cannot attach itself to invertebrates, such as insects, spiders, or octopi. A fungal carapace is treated as a dungeon hazard, and the unfortunate creature that it bonds with gains the coffin shell template.

Fungal Carapace (CR 1)

A fungal carapace occupies a 5-foot space. Once a round, a fungal carapace can make a single melee touch attack with a +3 bonus against any creature within 5 feet. Whenever a carapace successfully strikes a target, or is struck by the unprotected flesh of a predator or attacker, it creates a sticky, gluey bond between the two creatures. The carapace automatically grapples any creature it hits with its touch attack, and automatically grapples any creature touching it with unprotected flesh. Opponents so grappled cannot get free while the carapace is alive. A fungal carapace that is attached to a prospective host but has not yet hardened its bond must be frozen or cut away (dealing damage to the victim as well). A typical carapace has 8 hp and is immune to fire.

If allowed to harden, this bond soon becomes permanent, and the carapace begins to spread its mass out over its host’s skin. This bonded, protective mass then hardens the host’s skin. A fungal carapace can cover any size creature given enough time, since it is transforming some of the host’s own flesh as well as spreading its own. This covering process takes a single day for Tiny or smaller creatures, two days for Small creatures, four days for Medium creatures, a week for Large creatures, two weeks for Huge creatures, three weeks for Gargantuan creatures, and up to a month for Colossal creatures. At the end of this process, the host permanently gains the coffin shell template (described below).

The carapace is a pure symbiont, thought to have been created by a demonic slime-lord long ago. Only the most desperate of the Underdark races will ever don one of the creatures, but slave-warriors among the derro and aboleth are sometimes forced to become hosts to the foul creatures.

When not attached to a host, the carapace can subsist for months on a diet of less-dangerous fungus and slime-molds.

Coffin Shell Creatures

A coffin shell creature results when a host body is inhabited by a fungal carapace (see above). Once the host is entirely covered, the fungal carapace cannot be removed without further damage to the host’s body; attempts to remove it with fire, knives, or healing spells only inflict damage to the host. After the carapace covers the entire skin of the host, the host body becomes noticeably thinner and paler; this is when many creature’s companions first notice any change.

Sample Coffin Shell Creature

This short, emaciated creature has sickly white skin, pallid yellow hair, and staring eyes that have no pupils. It looks a bit like a twisted dwarf and a bit like a small, wracked human.

Coffin Shell Derro CR 4

CN Small plant (augmented monstrous humanoid)

Init +6; Senses darkvision 60 ft, low-light vision; Listen +1, Spot -3

Languages Common, Dwarven, Undercommon

AC 21, touch 13, flat-footed 19
(+1 size, +2 Dex, +4 natural, +3 studded leather armor, +1 buckler)

hp 13 (3 HD); fast healing 3

Immune confusion, insanity; plant traits

SR 15

Fort +1, Ref +5, Will +6

Weakness vulnerability to sunlight

Spd 20 ft

Melee short sword +4 (1d4/19-20)

Ranged repeating light crossbow +6 (1d6/19-20 plus poison)

Space 5 ft; Reach 5 ft

Base Atk +3; Grp -1

Atk Options Blind-Fight, poison (DC 12, 1d4 Str/1d4 Str), sneak attack +1d6

Spell-Like Abilities (CL 3rd)

At will—darkness, ghost sound

1/day—daze (DC 13), sound burst (DC 15)

Abilities Str 11, Dex 14, Con 11, Int 10, Wis 5, Cha 16

SQ debilitating bond, madness, poison use

Feats Blind-Fight, Improved Initiative

Skills Bluff +5, Hide +10, Listen +1, Move Silently +8

Possessions studded leather armor, buckler, short sword, repeating light crossbow, 20 bolts, 5 doses Medium monstrous spider venom

Debilitating Bond (Ex) Each week the coffin shell derro must make a DC 15 Fortitude save or take 1 point of Constitution drain.

Madness (Ex) Coffin shell derro use their Charisma modifier on Will saves instead of their Wisdom modifier, and have immunity to confusion and insanity effects. A coffin shell derro cannot be restored to sanity by any means short of a miracle or wish spell.

Plant Traits Immune to all mind-affecting effects (charms, compulsions, phantasms, patterns, and morale effects), poison, sleep effects, paralysis, polymorph, and stunning. Not subject to critical hits.

Poison Use (Ex) Coffin shell derro are not at risk of poisoning themselves when handling poison.

Sneak Attack (Ex) Any time a coffin shell derro’s opponent is denied his Dexterity bonus to AC, or if a coffin shell derro flanks his opponent, he deals an extra 1d6 points of damage. This ability is just like the rogue’s sneak attack and subject to the same limitations.

Vulnerability to Sunlight (Ex) A coffin shell derro takes 1 point of Constitution damage for every hour it is exposed to sunlight, and it dies if its Constitution score reaches 0. Lost Constitution points are recovered at the rate of 1 per every 24-hour period spent underground or otherwise sheltered from the sun.

Creating a Coffin Shell Creature

“Coffin Shell” is an acquired template that can be added to any living vertebrate animal, dragon, fey, giant, humanoid, magical beast, or monstrous humanoid creature (referred to hereafter as the base creature).

A coffin shell creature uses all the base creature’s statistics and special abilities except as noted here.

Size and Type: The creature’s type changes to plant and it gains the appropriate augmented subtype. Do not recalculate base attack bonus, saves, or skill points. Size is unchanged.

Special Qualities: A coffin shell creature retains all the special qualities of the base creature and gains those described below.

Fast Healing (Ex): A coffin shell creature heals 3 points of damage each round so long as it has at least 1 hit point.

Debilitating Bond (Ex): Each week the coffin shell creature must make a DC 15 Fortitude save or take 1 point of Constitution drain.