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 Invasion^B, 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)

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