Demonhive Queen (CR 6)

Large Outsider (Evil and Extraplanar)
Alignment: Always neutral evil
Initiative: -1(Dex); Senses: darkvision 60 ft., Listen +14, and Spot +14

AC: 15 (-1 size, -1 Dex, +7 natural), touch 8, flat-footed 16
Hit Dice: 8d8+78 (114 hp)
Fort +14, Ref +5, Will +9
Speed: 20 ft.
Space: 10 ft.; Reach 5 ft.
Base Attack +8; Grapple +15
Attack: Melee: bite +10 (3d6+4)
Special Attacks/Actions: maternal scream
Attack Options: aligned strike (evil)
Abilities: Str 17, Dex 9, Con 27, Int 2, Wis 16, Cha 2
Special Abilities: Immune: sonic
Special Qualities: hive mind
Feats: Improved Toughness, Toughness (2),
Skills: Climb +14, Listen +14, Spot +14, and Survival +14
Advancement: 9-11 HD (Large), 12-24 (Huge)
Climate/Terrain: The Abyss, any temperate or warm forest or jungle
Organization: Demonhive
Treasure/Possessions: None

Source: Monster Manual IV

Maternal Scream (Ex): The first time each round a demonet swarm is dispersed or destroyed, a demonhive queen lets loose a terrible screech as an immediate action. If all her demonet swarms are dead, a demonhive queen screams once per round as a free action. This effect deals 3d6 points of sonic damage to all creatures within 60 feet. Creatures in the area can attempt a DC 22 Fortitude save to take half damage. The save DC is Constitution-based.

Hive Mind (Ex): All demonhive members within 2 miles of a demonhive queen are in constant communication. If one is aware of a particular danger, they all are. If one in an encounter is not flat-footed, none of them are. No demonhive member in an encounter is considered flanked unless all of them are.

A demonhive queen is the heart of the hive and exists only to perpetuate its wanton destruction. Demonhive attendants serve and protect the queen, but she cares little for them. Instead, she values the demonets from which a new queen might arise.

First seen on one of the Infinite Layers of the Abyss, demon-hives are now found throughout the Lower Planes. With their aggressive and bloodthirsty members, demonhives threaten all creatures they encounter and lay waste to the areas they inhabit. If they were allowed to continue their rampage unchecked, demonhives might spread across entire planes.

Evil Subtype

A subtype usually applied only to outsiders native to the evil-aligned Outer Planes. Evil outsiders are also called fiends. Most creatures that have this subtype also have evil 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 an evil alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the evil subtype overcomes damage reduction as if its natural weapons and any weapons it wields were evil-aligned (see Damage Reduction).

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.