Inspired by the old tales that cancer was caused by an evil crab within. I actually designed this 4 years ago as one of my first creations and fixed it up from the original mess.
Tiny Outsider (chaos, evil, extraplanar)
Hit Dice: 3d8+18 (31)
Speed: 20 ft. (4 squares), swim 10 ft.
Armor Class: 18 (+1 dex, +5 natural, +2 size), touch 13, flat-footed 17
Base Attack/Grapple: +2/+2
Attack: Claw +5 melee (1d2 + diseased touch)
Full attack: Claw +5 melee (1d2 + diseased touch)
Space/Reach: 2 1/2 ft.0 ft.
Special Attacks: Diseased touch, true infection
Special Qualities: Amphibious, darkvision 60 ft., immune to acid, disease and poison, low-light vision, outsider traits, regeneration 5, scent
Saves: Fort +9, Ref +4, Will +5
Abilities: Str 10, Dex 12, Con 22, Int 10, Wis 14, Cha 6
Skills: Balance +6, Climb +5, Hide +6, Knowledge (the planes) +5, Listen +7, Move Silently +6, Spot +7, Swim +5
Feats: Improved Grapple, Tomb-tainted Soul
, Weapon Finesse(B)
Environment: Grey Wastes of Hades
Challenge Rating: 4
Alignment: Always Chaotic Evil
Advancement: 4-7 HD (Tiny), 8-12 HD (Small)
Level Adjustment: -
Cancer appears as a large, platter-sized crab of a murky brownish-green color. Its entire form seems disproportionate and slightly skewed. Its thick, armored shell is flat and has a cruel assortment of serrated edges and spines along the edge. One overly long arms ends in a glinting, stabbing claw that reaches out from its front section, while the other is tiny and atrophied. It is supported by eight segmented legs, all of slightly different lengths, that come to a needle-sharp point. From its front grow a pair of vicious mouth parts, made for tearing. Partially within the shell peer two tiny, distorted eyes, blazing redly with malevolence.
Diseased chaos embodied, these demonic entities have plagued the world since time immemorable. Having spread from their home plane they take great joy in causing misery to all those they come across. Many use their victims to spy on others, infecting them as they sleep and hiding within their bodies as their host goes about his business.
Cancer weighs 2 lbs. It speaks Abyssal.
Cancer prefers to approach with stealth and latch onto their victims and dig into their flesh, causing intense pain and suffering for as long as possible before its victim dies.
If this proves unsuccessful they will prod and pierce at the victim and try to grab hold boldly. If the odds are against the crabbish demon it will quickly flee, and follow its prey in secret, waiting for an opening.
Cancer's weapons are considered Chaotic and Evil for the purpose of overcoming damage reduction.
Diseased Touch (Ex):
Every hit by Cancer deals 1d4 extra damage as the wound festers and the skin about it becomes lumpy and sloughs off. Unless a DC 17 fortitude save is made, this damage does not heal on its own unless the area is cut out. The save DC is constitution based.
Fire and cold deals normal damage to cancer. If cancer loses a limb or body part, the lost portion regrows in 3d6 minutes. The creature can reattach the severed member instantly by holding it to the stump.
True Infection (Su):
If cancer succeeds on a grapple check it can attempt to burrow into its victim's flesh. The target must make a DC 17 fortitude check or cancer disappears within, dealing 2d6 damage and causing the victim to become Nauseated for 1d6 minutes. The wound closes immediately behind the crab. Each day the target takes 1d4 points of Constitution damage and is Sickened (DC 17 fortitude save halves and the victim is not sickened). At will it can deal from anywhere to 1 to 2d6 points of damage to it's victim, depending on it's wishes. The creature itself can only be driven out by a Remove Disease spell cast upon the target within a Magic Circle Against Evil/Chaos. The demon is not killed by these, and will attempt to reinfect its victim as soon as possible. Dictum and Holy Word directed at the host will kill the cancer if it fails its save. Cancer can see and hear normally while within its victim. Cancer gains a +4 racial bonus to grapple checks, which has already been included in the stat-block above. The save DC is constitution based.
If cancer is bitten the opponent must succeed on a save as well or it infects them, the torn flesh regenerating into a much smaller cancer. Those that swallow cancer whole gain no save against infection.