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Rot Grub, Giant Rot Grub

This twitching, pale maggot is the size of a large dog. A circular mouth quivers and gasps at one end of its pulsating body.

Giant Rot Grub CR 3

Source Bestiary 3 pg. 215, Pathfinder #25: The Bastards of Erebus pg. 78
XP 800
N Small vermin
Init +1; Senses blindsense 30 ft.; Perception +0


AC 15, touch 12, flat-footed 14 (+1 Dex, +3 natural, +1 size)
hp 34 (4d8+16)
Fort +8, Ref +2, Will +1
Immune mind-affecting effects


Speed 20 ft.
Melee bite +6 (1d6+3 plus poison and grab)
Special Attacks gnaw, grab (Medium)


Str 14, Dex 12, Con 18, Int —, Wis 10, Cha 1
Base Atk +3; CMB +4 (+8 grapple); CMD 15


Environment any
Organization solitary, pair, or nest (3–8)
Treasure none

Special Abilities

Gnaw (Ex) A rot grub that is grappling a foe and chooses to damage the foe with an additional grapple check deals twice its normal bite damage (2d6+6 for most giant rot grubs), in addition to injecting an additional dose of poison with each successful check.

Poison (Ex) Bite—injury; save Fort DC 16; frequency 1/round for 5 rounds; effect 1d3 Str; cure 1 save.


Rot grubs are foul, nauseating parasites that feed on flesh and use corpses as nests in which to grow. While a rot grub can derive nourishment from dead flesh, its true hunger is for the flesh of the living. Thankfully, rot grub swarms occur only rarely, as they require the infested carcass of a Huge or larger creature and many weeks to build up the numbers necessary to constitute a swarm.

In some cases, a rot grub continues to feed and grow, eventually reaching enormous size as a giant rot grub.

Creatures in "Rot Grub" Category

Giant Rot Grub3
Rot Grub Swarm7

Rot Grub

Source Pathfinder #25: The Bastards of Erebus pg. 78

Rot Grubs As Hazards (Cr 4)

Smaller groups of normal-sized rot grubs do not constitute a swarm, but even individually they're quite dangerous. Generally, a handful of the grubs infest a single corpse at a time, and a DC 15 Perception check is enough to note the infestation before the grubs have a chance to attack anything living that comes in contact with the corpse. If the Perception check is failed, 1d6 grubs swiftly burst from the carcass to burrow into the creature, which can attempt a DC 15 Ref lex save to avoid the grubs (but only if the creature is aware of the grubs' presence).

Once rot grubs are burrowing in a living body, the host must make a DC 17 Fortitude save each round. Failure results in 2 points of Constitution damage per grub infesting the victim—at Constitution 0, the rot grubs have reached the host's heart, brain, and other key internal organs and death occurs.

On the first round of infestation, applying flame to the point of entry can kill the grubs and save the host, but this inflicts 1d6 points of fire damage to the victim. Cutting the grubs out also works, but the longer the grubs remain in a host, the more damage this method does. For each round that the grubs have remained in a host, cutting them out requires a slashing weapon and a DC 20 Heal check, and inflicts 1d6 points of damage per round that the host has been infested. On a successful Heal check, the grubs are removed. A remove disease spell (or similar effect) instantly halts the infestation, but as the grubs themselves are parasites, immunity to disease offers no protection against infestation. Any amount of damage reduction is enough to provide immunity to infestation, however.

Infested Undead

Since rot grubs only feed on living flesh and use dead flesh as an incubator, undead are not harmed by infestations of the parasites. A corporeal, non-skeletal undead infested with rot grubs transfers one rot grub to any creature that touches it or to any creature it strikes with a touch attack or with any natural attack. The target may make a DC 15 Reflex save to avoid being infested, but otherwise is immediately subjected to a single grub burrowing through his flesh. A rot-grub-infested undead's CR increases by +1.