Void Hound, Slayer (CR 11)

Huge Magical Beast (Extraplanar and Void)
Alignment: Always neutral evil
Initiative: +4; Senses: darkvision 120 ft. and low-light vision

AC: 17 (-2 size, +9 natural), touch 8, flat-footed 17
Hit Dice: 16d10+112 (200 hp)
Fort +17, Ref +10, Will +5
Speed: 60 ft.
Space: 15 ft./10 ft.
Base Attack +16; Grapple +36
Attack: Bite +26 or slice charge +26
Full Attack: Bite +26 plus 2 claws +24 or slice charge +26
Damage: Bite 4d8+12, claws 3d6+6, slice charge 3d6+18 plus wounding
Special Attacks/Actions: Slice charge, wounding
Abilities: Str 34, Dex 10, Con 24, Int 4, Wis 10, Cha 6
Special Qualities: immunity to energy drain, void subtype
Feats: Improved Bull Rush; Improved Initiative; Improved Natural Attack (bite); Improved Natural Attack (claw); Multiattack; Power Attack
Skills: Hide +8 and Move Silently +11
Advancement: 17-24 HD (Huge)
Climate/Terrain: Any
Organization: Solitary or pack (1d8)
Treasure/Possessions: None

Source: Web

Slayers are simply Huge seeker hounds. They have the following change to their combat profile:

Wounding (Ex): A hit from the slayer's slice charge deals 1d4 points of Constitution damage from blood loss when it hits a creature. A critical hit does not multiply the Constitution damage. Creatures immune to critical hits (such as plants and constructs) are immune to the Constitution damage dealt by the slice charge.

Skills: A void hound has a +8 racial bonus on Hide checks.

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.