An enormous were wolf shaped shadow.

A masive were wolf shaped shadow with horns of one foot long each, stands at the height of 7 feet, and powerful claws. It eats anything living besides it's own kind. When not fighting it is either training, studying, eating, or sleeping. The only place and time that you can find it is at night in the darkest shadows of any place.

Combat
It fights very aggressively, it prefers to use it's poisonous shadow blade, and if it is lost or broken it will give a deadly strike from it's claws and massive horns. The mind of the shadow wolf works very fast, it times every attack while dodging them, and when an attack is timed just right it will use to it's advantage and find a weak point to strike upon. It's favorite tactic is to hide and wait for unexpecting beings and then strikes repeadiatly until it is dead.

Energy Drain (Su): This attack saps a living opponent’s vital energy and happens automatically when a melee or ranged attack hits. Each successful energy drain bestows one or more negative levels (the creature’s description specifies how many). If an attack that includes an energy drain scores a critical hit, it drains twice the given amount. Unless otherwise specified in the creature’s description, a draining creature gains 5 temporary hit points (10 on a critical hit) for each negative level it bestows on an opponent. These temporary hit points last for a maximum of 1 hour. An affected opponent takes a –1 penalty on all skill checks and ability checks, attack rolls, and saving throws, and loses one effective level or Hit Die (whenever level is used in a die roll or calculation) for each negative level. A spellcaster loses one spell slot of the highest level of spells she can cast and (if applicable) one prepared spell of that level; this loss persists until the negative level is removed. Negative levels remain until 24 hours have passed or until they are removed with a spell, such as restoration. If a negative level is not removed before 24 hours have passed, the affected creature must attempt a Fortitude save (DC 10 + 1/2 draining creature’s racial HD + draining creature’s Cha modifier; the exact DC is given in the creature’s descriptive text). On a success, the negative level goes away with no harm to the creature. On a failure, the negative level goes away, but the creature’s level is also reduced by one. A separate saving throw is required for each negative level.
Frightful Presence (Ex): This special quality makes a creature’s very presence unsettling to foes. It takes effect automatically when the creature performs some sort of dramatic action (such as charging, attacking, or snarling). Opponents within range who witness the action may become frightened or shaken. Actions required to trigger the ability are given in the creature’s descriptive text. The range is usually 30 feet, and the duration is usually 5d6 rounds. This ability affects only opponents with fewer Hit Dice or levels than the creature has. An affected opponent can resist the effects with a successful Will save (DC 10 + 1/2 frightful creature’s racial HD + frightful creature’s Cha modifier; the exact DC is given in the creature’s descriptive text). An opponent that succeeds on the saving throw is immune to that same creature’s frightful presence for 24 hours. Frightful presence is a mind-affecting fear effect.
Poison (Ex): Poison attacks deal initial damage, such as ability damage (see page 305) or some other effect, to the opponent on a failed Fortitude save. Unless otherwise noted, another saving throw is required 1 minute later (regardless of the first save’s result) to avoid secondary damage. A creature’s descriptive text provides the details.A creature with a poison attack is immune to its own poison and the poison of others of its kind.The Fortitude save DC against a poison attack is equal to 10 + 1/2 poisoning creature’s racial HD + poisoning creature’s Con modifier (the exact DC is given in the creature’s descriptive text).A successful save avoids (negates) the damage.
Change Shape (Su): A creature with this special quality has the ability to assume the appearance of a specific creature or type of creature (usually a humanoid), but retains most of its own physical qualities. A creature cannot change shape to a form more than one size category smaller or larger than its original form. Changing shape results in the following changes to the creature: