Banelar (CR 7)

Huge Magical Beast
Alignment: Usually lawful evil
Initiative: +5 (+1 Dex, +4 Improved Initiative); Senses: darkvision 60 ft., low-light vision, and Spot +13

AC: 14 (-2 size, +1 Dex, +5 natural), touch 9, flat-footed 13
Hit Dice: 7d10+35 (73 hp)
Fort +10, Ref +6, Will +7
Speed: 30 ft., swim 30 ft.
Space: 15 ft./15 ft.
Base Attack +7; Grapple +23
Attack: Sting +13 melee, bite +8 melee
Full Attack: Sting +13 melee, bite +8 melee
Damage: Sting 2d4+8 plus poison, bite 1d3+4 plus poison
Special Attacks/Actions: Spells, poison, magic items
Abilities: Str 26, Dex 13, Con 21, Int 17, Wis 16, Cha 16
Special Qualities: Fast healing 2, poison and acid immunity, resist petrification
Feats: Improved Initiative; Iron Will; Spell Focus (Enchantment)
Skills: Concentration +15, Diplomacy +13, Intimidate +13, Spot +13, Swim +16, and Use Magic Device +13
Advancement: 8-15 HD (Huge); 16-21 HD (Gargantuan)
Climate/Terrain: Warm and temperate land and aquatic
Organization: Solitary or band (2-5)
Treasure/Possessions: Standard

Source: Monster Compendium: Monsters of Faerûn

Spells: Banelars have the spellcasting abilities of a 6th-level cleric (with access to the Evil, Magic, and Water domains) and a 6th-level wizard. All of a banelar's spells have only verbal components, and a banelar can cast a single spell every round as a free action while attacking.

Poison (Ex): Those hit by a banelar's bite or tail attack must succeed at a Fortitude save (DC 18) or be injected with poison. The initial damage is 2d4 points of temporary Constitution damage and the secondary damage is unconsciousness for 1d3 hours. As a side effect of the poison, the victim's skin turns blue around the wound.

Magic Items: Banelars collect magic items and use them freely. Their tentacles can wear or manipulate amulets, rings, wands, rods, potions, and similar small items.

Resist Petrification (Ex): Banelars gain a +3 bonus on their saving throws to resist petrification.

A banelar's physical attacks are its bite and the stinger at the end of its tail, both of which inject venom into its prey. Banelars have a wide range of magical abilities to complement these attacks as well.