Medusa, Amphibious* (CR 7)

Medium Monstrous Humanoid (Aquatic)
Alignment: Usually lawful evil
Initiative: +1 (Dex); Senses: darkvision 60 ft. and Spot +8

AC: 14 (+1 Dex, +3 natural), touch 11, flat-footed 13
Hit Dice: 6d8+6 (33 hp)
Fort +3, Ref +6, Will +6
Speed: 30 ft., swim 15 ft.
Space: 5 ft./5 ft.
Base Attack +6; Grapple +6
Attack: Light crossbow +7 ranged or dagger +7 melee or snakes +7 melee
Full Attack: Light crossbow +7 ranged, or dagger +7/+2 melee and snakes +2 melee
Damage: Light crossbow 1d8/19-20, dagger 1d4/19-20, snakes 1d4 plus poison
Special Attacks/Actions: Petrifying gaze, poison
Abilities: Str 10, Dex 13, Con 12, Int 12, Wis 13, Cha 15
Special Qualities: Amphibious
Feats: Point Blank Shot; Precise Shot; Weapon Finesse
Skills: Bluff +9, Diplomacy +4, Disguise +9 (+11 acting), Intimidate +4, Move Silently +7, Spot +8, and Swim +8
Advancement: By character class
Climate/Terrain: Temperate aquatic
Organization: Solitary or covey (2-4)
Treasure/Possessions: Double standard

Source: Stormwrack

Petrifying Gaze (Su): Turn to stone permanently, 30 feet, Fortitude DC 15 negates. The save DC is Charisma-based.

Poison (Ex): Injury, Fortitude DC 14, 1d6 Str/2d6 Str. The save DC is Constitution-based.

Skills: An amphibious medusa has a +8 racial bonus on any Swim check to perform some special action or avoid a hazard. It can always choose to take 10 on a Swim check, even if distracted or endangered. It can use the run action while swimming, provided it swims in a straight line.

An amphibious medusa tries to disguise its true nature until the intended target is within range of its petrifying gaze, using subterfuge and bluffing games to convince the target that there is no danger. It uses normal weapons to attack those who avert their eyes or survive its gaze, while its poisonous snakes strike at adjacent opponents.

Aquatic Subtype

Creatures with the aquatic subtype always have swim speeds and thus can move in water without making Swim checks. An aquatic creature can breathe underwater. It cannot also breathe air unless it has the amphibious special quality.