Potamotherium

Medium Beast, Unaligned
Challenge 3 (700 XP)  Proficiency Bonus +2

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Armor Class 14 (Natural Armor)

Hit Points 60 (8d8 + 24)

Speed 30 ft., swim 40 ft.

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STR	DEX	CON	INT	WIS	CHA
14 (+2)	16 (+3)	16 (+3)	2 (–4)	14 (+2)	6 (–2)

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Saving Throws

Dex +5, Wis +4

Skills

Perception +4, Stealth +5, Athletics +4

Senses

Darkvision 60 ft., Passive Perception 14

Languages

—

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Amphibious Predator

The Potamotherium can breathe both air and water and can remain submerged for up to 30 minutes.

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Keen Hearing and Smell

The Potamotherium has advantage on Wisdom (Perception) checks that rely on hearing or smell.

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Aquatic Ambusher

If the Potamotherium is submerged and unseen when combat begins, it has advantage on its first attack and that attack deals an additional 2d6 damage.

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Death Roll (Recharge 5–6)

If the Potamotherium has a creature grappled, it can initiate a spinning thrash in the water. The grappled creature must succeed on a DC 14 Strength saving throw or take 2d10 bludgeoning damage and become restrained until the end of its next turn. On a success, the target takes half damage and isn’t restrained.

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Hold Breath

The Potamotherium can hold its breath for up to 30 minutes.

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Actions

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Multiattack

The Potamotherium makes two attacks: one with its bite and one with its claws.

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Bite

Melee Weapon Attack: +5 to hit, reach 5 ft., one target.
Hit: 8 (1d10 + 3) piercing damage. If the target is Medium or smaller, it is grappled (escape DC 13). Until this grapple ends, the Potamotherium can’t bite another target.

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Claw

Melee Weapon Attack: +5 to hit, reach 5 ft., one target.
Hit: 7 (1d8 + 3) slashing damage.

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Tactics

• Stealth and Surprise: The Potamotherium favors ambush tactics, hiding in water or under natural cover. It may remain completely motionless for hours, waiting for prey to approach the shoreline.
• Target Selection: It prioritizes solitary, wounded, or distracted targets, dragging them underwater to isolate and kill them quickly.
• Combo Predator: It will use its bite to grapple a target and follow up with its Death Roll as soon as it becomes available.
• Evasive Retreat: If heavily injured or outnumbered, it flees into submerged tunnels, reeds, or sunken root systems to escape pursuit.

Potamotherium

This sleek, muscular predator glides through rivers with otter-like grace. Its elongated snout bristles with needle-sharp teeth, and its amber eyes watch the shore with ancient, calculating stillness.

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Potamotherium  CR 3
XP 800
N Medium animal
Init +3; Senses darkvision 60 ft., low-light vision, scent; Perception +8

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DEFENSE

AC 15, touch 13, flat-footed 12 (+2 natural, +3 Dex)
hp 34 (4d8+16)
Fort +7, Ref +7, Will +3
Defensive Abilities hold breath (30 minutes)

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OFFENSE

Speed 30 ft., swim 40 ft.
Melee bite +6 (1d8+3 plus grab), claw +6 (1d6+3)
Space 5 ft.; Reach 5 ft.
Special Attacks aquatic ambush, death roll

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STATISTICS

Str 16, Dex 17, Con 18, Int 2, Wis 14, Cha 6
Base Atk +3; CMB +6 (+10 grapple); CMD 19 (23 vs. trip)
Feats Toughness, Weapon Focus (bite)
Skills Perception +8, Stealth +8, Swim +11
SQ amphibious, keen senses

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ECOLOGY

Environment cold rivers, forested wetlands, freshwater lakes
Organization solitary, pair, or den (2–4)
Treasure none (but dens often contain bones, shiny objects, or lost equipment)

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SPECIAL ABILITIES

Amphibious (Ex):
Although it breathes air, a Potamotherium can survive equally well in water or on land.

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Aquatic Ambush (Ex):
When attacking a creature that has not yet acted in combat and while submerged, a Potamotherium deals an additional 2d6 points of damage with its first successful melee attack. If it successfully grapples a target with this attack, it may immediately pull the creature 5 feet toward itself or into the water, if applicable.

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Death Roll (Ex):
Once per round, while grappling a creature in water, the Potamotherium can initiate a thrashing spin as a free action. It attempts a combat maneuver check to maintain the grapple. If successful, it deals 2d6 bludgeoning damage, and the target must succeed at a DC 15 Fortitude save or become staggered for 1 round.
The save DC is Constitution-based.

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Hold Breath (Ex):
A Potamotherium can hold its breath for up to 72 rounds (approximately 7 minutes), allowing it to lie submerged and motionless for extended ambushes.

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Keen Senses (Ex):
The Potamotherium’s enhanced senses grant it low-light vision, scent, and a +4 racial bonus on Perception checks.

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TACTICS

Before Combat:
Potamotheria remain completely still beneath the surface, hiding in reeds or submerged logs. They prefer to attack at twilight, when shadows distort depth and visibility.

During Combat:
They strike with a surprise bite, attempting to grapple and drag prey into the water, immediately following with Death Roll. They prioritize vulnerable or isolated foes and will use terrain to stay submerged between strikes.

Morale:
If reduced below 10 hit points or if a battle turns against it, a Potamotherium attempts to retreat into underwater burrows, tunnels, or dense reeds to escape.

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DESCRIPTION

The Potamotherium is a relic of ancient evolution, a transitional predator between land and sea. Though it resembles an oversized otter, its cunning and aggression exceed that of most natural animals. It is revered and feared in remote riverfolk traditions as a guardian, a spirit of drowned things, or a killer that drags the unwary into dark water.

Its bones have been found in fossil strata across old empires, leading sages to speculate on its role as an ancestor to seals, sea lions, or stranger aquatic beasts long since vanished.

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Variant: Elder Potamotherium (CR 5)

Larger specimens grow to over 8 feet in length and weigh nearly 500 pounds. These creatures have 5 HD, the Improved Grab ability, and Swallow Whole (1d6+4 damage, AC 14, hp 12). Some may develop rudimentary problem-solving intelligence (Int 4) and a near-territorial hatred for humanoids.

Potamotherium

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This sleek, muscular predator moves with uncanny silence. With the body of an otter and the instincts of a crocodile, it waits beneath the water’s surface, ready to drag its prey into the depths.

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Potamotherium
Medium Animal
Hit Dice: 4d8+12 (30 hp)
Initiative: +3
Speed: 30 ft. (6 squares), swim 40 ft.
Armor Class: 16 (–0 size, +3 Dex, +3 natural), touch 13, flat-footed 13
Base Attack/Grapple: +3/+6
Attack: Bite +6 melee (1d8+3 plus grab)
Full Attack: Bite +6 melee (1d8+3 plus grab) and 2 claws +4 melee (1d4+1)
Space/Reach: 5 ft./5 ft.
Special Attacks: Grab, death roll, aquatic ambush

Special Qualities: Low-light vision, darkvision 60 ft., hold breath, scent
Saves: Fort +7, Ref +7, Will +2
Abilities: Str 16, Dex 17, Con 16, Int 2, Wis 14, Cha 6
Skills: Hide +7, Listen +6, Spot +6, Swim +11
Feats: Weapon Focus (bite), Toughness
Environment: Temperate or cold rivers, swamps, and wetlands
Organization: Solitary, pair, or den (2–4)
Challenge Rating: 3
Treasure: None (but see Ecology)
Alignment: Always neutral
Advancement: 5–6 HD (Medium); 7–9 HD (Large)
Level Adjustment: —

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Combat

A Potamotherium hunts by stealth, striking from concealment in water. It uses grab to lock onto prey and immediately attempts to death roll if submerged. It avoids prolonged combat and flees if outmatched.

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Aquatic Ambush (Ex):
If the Potamotherium is submerged and unseen when combat begins, its first successful melee attack deals an additional 2d6 damage and the target must succeed on a DC 13 Reflex save or be flat-footed until the end of the Potamotherium’s next turn. The save DC is Dexterity-based.

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Grab (Ex):
If the Potamotherium hits with its bite, it may attempt to start a grapple as a free action without provoking an attack of opportunity. If it wins the grapple check, it establishes a hold and can attempt a death roll on the following round.

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Death Roll (Ex):
While grappling a creature in water, the Potamotherium may thrash violently as a free action once per round. The target must succeed on a DC 15 Fortitude save or take 2d6 bludgeoning damage and become staggered for 1 round. On a successful save, the target takes half damage and is not staggered.
The save DC is Constitution-based.

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Hold Breath (Ex):
The Potamotherium can hold its breath for up to 64 rounds (about 6.5 minutes).

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Skills

Potamotherium has a +8 racial bonus on Swim checks and may always take 10 on Swim checks, even if rushed or threatened. It uses Dexterity instead of Strength for Swim checks. It gains a +4 racial bonus on Hide checks when submerged in water or muddy terrain.

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Tactics

• Before Combat: Hides in shallow water, among reeds or submerged logs. Prefers dusk or misty conditions.
• During Combat: Opens with a bite and grab, then initiates a death roll if underwater. Focuses on isolated or lightly armored foes.
• Morale: If reduced to 10 hp or fewer, or if facing fire or ranged magic, it attempts to escape into deep water or a burrow.

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Ecology

Potamotheria are relic predators from an ancient era. Though they resemble massive otters, their behavior is closer to crocodilians. They dwell in underwater burrows or hidden grottoes and hoard bones, shiny rocks, and occasionally drowned trinkets. In regions where they are common, superstitious locals speak of “river demons” that punish those who disrespect the water.

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Lore

Knowledge (Nature)

• DC 15: This is a Potamotherium, a powerful aquatic predator. It hunts by ambush and grapples prey.
• DC 20: It is known for its spinning death roll, used to disorient and break struggling victims.
• DC 25: Though an animal, its ancient lineage makes it a subject of fascination to druids, who sometimes protect their dens as sacred sites.