The waves call to you, like a siren’s song echoing across crashing surf.
The corruption of the deep ones typically comes in two varieties. The most common source of deep one corruption is having dormant deep one blood running through your veins.
Exposure to the magic of cults dedicated to Great Old Ones like Cthulhu could awaken this dormant lineage within you, beginning your transformation into a deep one. Likewise, exposure to the presence of deep ones themselves can cause you to heed a call to deep waters that ends with a torturous transformation. Less common means of contracting a deep one corruption include ritualistic transformation, curses, or—in extreme cases—willing copulation with a deep one.
Once the deep one corruption has taken root, the summons calling you to the deep ones’ cold, lightless realm becomes a constant thrum in the back of your mind. Exposure to sea water becomes increasingly important to you. Each day that you don’t spend at least 1 hour per manifestation level fully immersed in the ocean or a salt-water sea, you must succeed at a Will save (DC = 15 + your manifestation level). You also need to attempt such a Will save whenever you are a target of (or in the area of ) a divine spell or spell-like ability with the evil descriptor.
Corruption Stage 1: The first time you fail, you lose control of yourself for 24 hours. When you regain your senses, you find yourself in the sea or an ocean, or at least on your way to such a place if you were too far away to reach it. Either way, your alignment shifts one step towards chaotic evil.
Corruption Stage 2: The second time you fail, you lose control again, and you find that you have made contact with an alien entity during the missing time. Your alignment shifts to chaotic evil and your race changes to deep one hybrid, if it wasn’t already. If you are already over the venerable age for a deep one hybrid (60 years), you experience the final change as per the race’s ability, becoming an NPC deep one under the GM’s control.
Corruption Stage 3: The third time you fail, you experience the final change early, becoming an NPC deep one under the GM’s control.
Removing the Corruption
Removing the deep one corruption might require psychic conditioning away from compulsions regarding water and necromantic rituals to expunge the deep one blood from your veins. The ritual might also require slaying the deep one who sired your bloodline.
The following are manifestations of the deep one corruption.
You gain a bite attack and can taste blood in the water.
Prerequisite(s): Deep adaptation*, loathsome gills*.
Gift: You gain a bite attack as a primary natural weapon.
This bite attack deals 1d6 points of damage if your size is Medium (1d4 if Small). Additionally, you gain the scent ability when underwater and can track a creature that travels underwater using a Perception check rather than a Survival check, so long as it was bleeding (either suffering from a bleed effect or having taken at least 1 point of piercing or slashing damage that was neither healed nor treated with a successful Heal check).
Stain: Your toothy maw distorts your speech, and your thoughts flit between potential prey. You take a 15% spell failure chance for spells with verbal or thought components and a –2 penalty on all Bluff, Diplomacy, Disguise, Handle Animal, and Perform checks.
Your slimy touch robs your victims of breath.
Prerequisite(s): Manifestation level 7th, claws of the deep*, swimmer in the deep*.
Gift: Once per day for every 2 manifestation levels you possess, you can attempt a touch attack that causes your opponent to suffocate. If this attack hits, the target must succeed at a Fortitude save or it gains the ability to breathe water, but also immediately loses the ability to breathe air and begins to suffocate unless it holds its breath. This effect lasts for a number of minutes equal to your manifestation level, and after each minute, the victim can attempt another Fortitude save to negate the effect. The DC of the save increases by 2 every minute.
Stain: You require constant submersion in salt water.
If you spend more than 1 day without fully submerging yourself in such water, you suffer internal organ failure, painful cracking of the skin, and death within 4d6 hours.
Disgusting, translucent claws grow from your fingers.
Prerequisite(s): Manifestation level 3rd, swimmer in the deep*.
Gift: You gain two claw natural attacks. These claws deal 1d4 points of damage if your size is Medium (1d3 if Small).
Stain: You exude a strong odor of low tide. This allows creatures with the scent ability to notice you from twice the usual distance, and makes it extremely difficult—and sometimes outright impossible—to disguise yourself.
You are acclimated to deep ocean pressures and temperatures.
Prerequisite(s): Loathsome gills*.
Gift: You gain cold resistance 5. At manifestation level 6th, you can survive safely at any ocean depth.
Stain: Your flesh peels away to reveal fine, iridescent scales, and your movements become slow and awkward. You take a –2 penalty to your Dexterity score while on land.
Your eyes grow accustomed to the dark places of the world.
Stain: Your eyes’ reflective sheen causes light sensitivity.
Your journey to the depths presaged your return to dry land.
Prerequisite(s): Manifestation level 7th, loathsome gills*.
Gift: You gain the aquatic subtype and the amphibious special quality. You gain a swim speed equal to half your land speed. If you have the swimmer in the deep manifestation, increase your swim speed by 10 feet instead.
Stain: Your hair falls out in patches and your skin takes on a slimy sheen. You take a –2 penalty to your Charisma score.
You grow gills at your jawline.
Gift: You can hold your breath underwater for 10 minutes per point of Constitution you have. At manifestation level 3rd, you can breathe underwater indefinitely. At manifestation level 7th, you can no longer breathe air and must hold your breath when above water (though you can still hold your breath for 10 minutes per point of Constitution you have).
Your senses are keener underwater.
Stain: Your eyes grow bulbous and fishlike. You take a –2 penalty on Perception checks while not underwater.
Your deep one blood runs thick and slowly, arresting aging.
Prerequisite(s): Manifestation level 5th.
Gift: You age more slowly than members of your base race.
It takes you twice as long to reach middle age, and three times as long to reach both old age and venerable. At manifestation level 8th, you gain a +2 bonus to your Constitution score.
Stain: You dream of lost cities in ages primordial and are haunted by strange aeons long since forgotten. You require 16 hours of sleep for a night’s rest and you are incapable of deriving benefit from effects that replace the need for sleep (like a ring of sustenance) or ameliorate, suppress, or remove the effects of lack of sleep.
The cold depths of the ocean are your home now.
Gift: You gain a +4 racial bonus on Swim checks (which doesn’t stack with the +8 racial bonus from having a swim speed) and can take a 10 on Swim checks even while threatened. At manifestation level 3rd, you gain a swim speed equal to half your land speed. At manifestation level 5th, your swim speed is equal to your land speed.
If you are a deep one hybrid, you instead gain a +10-foot enhancement bonus to your swim speed.
Pathfinder Roleplaying Game Horror Adventures © 2016, Paizo Inc.; Authors: John Bennett, Clinton J. Boomer, Logan Bonner, Robert Brookes, Jason Bulmahn, Ross Byers, Jim Groves, Steven Helt, Thurston Hillman, Eric Hindley, Brandon Hodge, Mikko Kallio, Jason Nelson, Tom Phillips, Stephen Radney-MacFarland, Alistair Rigg, Alex Riggs, David N. Ross, F. Wesley Schneider, David Schwartz, Mark Seifter, and Linda Zayas-Palmer.