Sinister (CR 3)

Large Magical Beast
Alignment: Usually neutral evil
Initiative: +1 (Dex); Senses: darkvision 60 ft., low-light vision, Listen +9, and Spot +9

AC: 17 (-1 size, +1 Dex, +4 deflection, +3 natural), touch 14, flat-footed 16
Hit Dice: 4d10+12 (34 hp)
Fort +7, Ref +5, Will +3
Speed: 10 ft., fly 50 ft. (perfect)
Space: 10 ft./5 ft.
Base Attack +4; Grapple +12
Attack: Bite +7 melee
Full Attack: Bite +7 melee
Damage: Bite 1d6+6
Special Attacks/Actions: Hold monster
Abilities: Str 19, Dex 13, Con 16, Int 12, Wis 14, Cha 13
Special Qualities: Missile deflection, SR 13
Feats: Alertness; Flyby Attack
Skills: Hide +2, Listen +9, Move Silently +7, and Spot +9
Advancement: 5-8 HD (Large); 9-12 HD (Huge)
Climate/Terrain: Any land and underground
Organization: Band (2-7)
Treasure/Possessions: None

Source: Monster Compendium: Monsters of Faerûn

Hold Monster (Sp): Sinisters can cast hold monster once per day. They usually save this ability for escaping from creatures more powerful than they are, but may use it when hunting if they are ravenous.

Missile Deflection (Su): Sinisters are surrounded by a 5-foot radius field of force that helps deflect melee attacks (represented a +4 deflection bonus to AC). In addition, this field stops missile attacks, turning away normal missiles and absorbing spells such Melf's acid arrow and magic missile.

Sinisters have a powerful bite, but their more potent abilities are magical in nature.