Formian Armadon (CR 8)

Large Outsider (Extraplanar and lawful)
Alignment: Always lawful neutral
Initiative: +5; Senses: Listen +12 and Spot +12
Languages: A forlorn husk speaks Common, as well as any languages it spoke when alive.

AC: 25 (-1 size, +1 Dex, +15 natural), touch 10, flat-footed 24
Hit Dice: 8d8+32 (68 hp)
Fort +10, Ref +7, Will +7
Speed: 40 ft.
Space: 10 ft./5 ft.
Base Attack +8; Grapple +18
Attack: Bite +13 melee
Full Attack: Bite +13 melee and 2 claws +11 melee and sting +11 melee
Damage: Bite 2d6+6/17-20/x3, claw 1d8+3, sting 2d4+3
Special Attacks/Actions: Acid spray, augmented critical, poison
Abilities: Str 22, Dex 13, Con 19, Int 10, Wis 12, Cha 11
Special Qualities: Acid immunity, hive mind, immunities, outsider traits, resistances, SR 20
Feats: Improved Critical (bite); Improved Initiative; Multiattack
Skills: Balance +12, Climb +17, Hide +8, Jump +17, Listen +12, Move Silently +12, Spot +12, and Survival +12
Advancement: 9-12 HD (Large); 12-24 (Huge)
Climate/Terrain: Any land and underground (Mechanus)
Organization: Solitary, team (2-4), or troop (6-11)
Treasure/Possessions: -

Source: Fiend Folio

Hive Mind (Ex): All formians within 50 miles of queen are in constant communication. If one is aware of a particular danger they all are. If one in a group is not flat-footed none of them are. No formian in a group is considered flanked unless all of them are.

Immunities (Ex): Formians have cold, petrification, and poison immunity.

Outsider Traits: Formians have darkvision (60-foot range), and they cannot be raised or resurrected (though a wish or miracle spell can restore life).

Resistances (Ex): All formians have fire, electricity, and sonic resistance 20.

Armadons rush into the thick of battle where they can do the most damage. They typically release a gout of acid prior to engaging in melee. Because they are immune to acid, they use their acid spray in areas with other armadons even if they are in combat.

Armadons can be summoned using a summon monster VII spell.

Acid Spray (Ex): An armadon can spray a 20-foot burst of acid from glands in its tail, dealing 3d8 points of acid damage to everything in the area. Once an armadon uses this ability, it cannot use it again for 1d4 rounds. A successful Reflex save (DC 17) halves the damage.

Augmented Critical (Ex): An armadon's bite attack threatens a critical hit on a natural attack roll of 17-20 because of the creature's augmented critical ability and its Improved Critical feat. On a successful critical hit with a bite, an armadon deals triple damage.

Poison (Ex): An armadon delivers its poison (Fort DC 18 negates) with each successful sting attack. Initial and secondary damage are the same (1d6 Str).

Extraplanar Subtype

A subtype applied to any creature when it is on a plane other than its native plane. A creature that travels the planes can gain or lose this subtype as it goes from plane to plane. This book assumes that encounters with creatures take place on the Material Plane, and every creature whose native plane is not the Material Plane has the extraplanar subtype (but would not have when on its home plane). An extraplanar creatures usually has a home plane mentioned in its description. These home planes are taken from the Great Wheel cosmology of the D&D game (see Chapter 5 of the Dungeon Master's Guide). If your campaign uses a different cosmology, you will need to assign different home planes to extraplanar creatures.

Creatures not labeled as extraplanar are natives of the Material Plane, and they gain the extraplanar subtype if they leave the Material Plane. No creature has the extraplanar subtype when it is on a transitive plane; the transitive planes in the D&D cosmology are the Astral Plane, the Ethereal Plane, and the Plane of Shadow.

Lawful Subtype

A subtype usually applied only to outsiders native to the lawful-aligned Outer Planes. Most creatures that have this subtype also have lawful alignments; however, if their alignments change, they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has a lawful alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the lawful subtype overcomes damage reduction as if its natural weapons and any weapons it wields were lawful-aligned (see Damage Reduction).