This tiny lizard possesses two front legs and no hind legs. A poison sack protrudes from its chin.

Hydrus CR 1/2

XP 200
N Tiny animal
Init +5; Senses low-light vision; Perception +6


AC 18, touch 17, flat-footed 13 (+5 Dex, +1 natural, +2 size)
hp 4 (1d8)
Fort +2, Ref +7, Will +2
Defensive Abilities acid resistance 2


Speed 20 ft., climb 10 ft., swim 40 ft.
Melee bite +7 (1d4-2 plus invasion)
Ranged spittle +7 (poison)
Space 2 1/2 ft.; Reach 0 ft.
Special Attacks burst, invasion, poison


Str 6, Dex 21, Con 10, Int 2, Wis 14, Cha 5
Base Atk +0; CMB +3 (+7 invasion); CMD 13
Feats Improved InvasionB, Weapon Finesse
Skills Perception +6; Racial Modifiers uses Dexterity for Climb and Swim


Burst (Ex)

A hydrus that has successfully invaded a creature will attempt to eat its way out, using its bite as a Tiny piercing weapon. It attacks from the inside each round (opponent’s Armor Class is equal to 10 + 1/2 the creature’s natural armor). It eats its way free after dealing 1/10 of the creature’s total hit points. Victims of a hydrus burst take an additional 1d6 bleed each round until they receive a DC 15 Heal check or any amount of magical healing.

Invasive (Ex)

A hydrus feeds by crawling inside a creature’s mouth and eating it from the inside. When a hydrus successfully hits an opponent, it may make an invasion combat maneuver as a free action that does not provoke an attack of opportunity. It adds its size modifier to combat maneuver checks as a bonus rather than a penalty. Once it crawls in the creature’s mouth and down its throat, the hydrus gains the grappled condition. Once inside, the hydrus will try to eat its way out (see Burst). A hydrus can only invade creatures that are at least one size category larger than itself.

Poison (Ex)

Spittle—contact; save Fort DC 11; frequency 1/round for 3 rounds; effect paralysis; cure 1 save.

The poison spittle of a hydrus has a 10 ft. range increment and is otherwise considered a thrown weapon.


Environment temperate or warm aquatic
Organization single, family (2-5) or horde (6-30)
Treasure none

Hordes of this tiny lizard are responsible for considerable damage. They swim into a village near a river and look for food under the cover of night. These little monsters can poison anyone not asleep, paralyzing them or feeding on anyone not moving. Less than five minutes later, the hydruses are swimming back to their homes with full bellies leaving behind victims paralyzed and unable to stop the bleeding. This can cause considerable unrest among the local population of the River Nations. While they are most frequently encountered in families and hordes, an individual hydrus has been known hunt on its own. When doing so, they prefer to feed upon small groups of creatures along riverbanks. More than one adventuring party has had their night watchman poisoned and attacked before they can raise an alarm.

An adult hydrus stands between three and five inches tall on its forelegs and can grow up to two feet long.

Section 15: Copyright Notice

Book of Beasts: Monsters of the River Nations, copyright 2010 Jon Brazer Enterprises; Author Steven Helt.

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