Naga, Bright (CR 3)

Large Aberration
Alignment: Usually chaotic evil
Initiative: +1 (Dex); Senses: darkvision 60 ft., Listen +12, and Spot +4
Languages: Common and Draconic

AC: 15 (-1 size, +1 Dex, +5 natural), touch 10, flat-footed 14
Hit Dice: 5d8+15 (37 hp)
Fort +4, Ref +2, Will +6
Speed: 40 ft.
Space: 10 ft./5 ft.
Base Attack +3; Grapple +9
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 2d6+3
Special Attacks/Actions: Mock spell
Abilities: Str 15, Dex 12, Con 17, Int 10, Wis 15, Cha 12
Special Qualities: -
Feats: Alertness; Combat Casting
Skills: Concentration +11 (casting defensively +15), Listen +12, and Spot +4
Advancement: 7-10 HD (Large); 11-15 HD (Huge)
Climate/Terrain: Warm mountains
Organization: Solitary, nest (2-4), or entourage (1 bright naga plus 2-5 troglodytes)
Treasure/Possessions: Standard

Source: Miniatures Handbook

Mock Spell (Sp): A bright naga can use the effect of one 1st-level sorcerer spell at will, as a 3rd-level sorcerer. This mock spell is magically imprinted in the bright naga's mind from an early age, and it cannot be changed. Magic missile is the most common mock spell, but bright nagas are also known to use burning hands, color spray, and virtually any other sorcerer spell. The spell's save DC, if appropriate, is 12. The save DC is Charisma-based. (With a Concentration modifier of +11 and the Combat Casting feat, a bright naga can cast defensively without risk of failure.)

Given a chance, a bright naga takes advantage of its labyrinthine lair, drawing enemies into an exasperating combat in which the naga appears, strikes, and disappears over and over again.