Naga, Water (CR 7)

Large Aberration (Aquatic)
Alignment: Usually neutral
Initiative: +1 (Dex); Senses: darkvision 60 ft., Listen +7, and Spot +7

AC: 15 (-1 size, +1 Dex, +5 natural), touch 10, flat-footed 14
Hit Dice: 7d8+28 (59 hp)
Fort +6, Ref +5, Will +8
Speed: 30 ft., swim 50 ft.
Space: 10 ft./5 ft.
Base Attack +5; Grapple +12
Attack: Bite +7 melee
Full Attack: Bite +7 melee
Damage: Bite 2d6+4 and poison
Special Attacks/Actions: Poison, spells
Abilities: Str 16, Dex 13, Con 18, Int 10, Wis 17, Cha 15
Special Qualities: -
Feats: Alertness; Combat Casting; Dodge; Eschew Materials; Lightning Reflexes
Skills: Concentration +12, Listen +7, Spellcraft +8, Spot +7, and Swim +11
Advancement: 8-10 HD (Large); 11-21 HD (Huge)
Climate/Terrain: Temperate aquatic
Organization: Solitary or nest (2-4)
Treasure/Possessions: Standard

Source: Monster Manual

Poison (Ex): Bite, Fortitude save (DC 17); initial and secondary damage 1d8 temporary Constitution.

Spells: Water nagas cast spells as 7th-level sorcerers but never use fire spells.

Nagas favor spells over other forms of combat. Because they are almost always found in the lairs they guard and know well, they can arrange most encounters to suit their wishes.

Water nagas prefer to stay mostly concealed in a body of water while they launch a spell attack.

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.