Energy Drain (Su): Living creatures hit by a wight's slam attack receive one negative level. The Fortitude save to remove the negative level has a DC of 14.

Create Spawn (Su): Any humanoid slain by a wight becomes a wight in 1d4 rounds. Spawn are under the command of the wight that created them and remain enslaved until its death. They do not possess any of the abilities they had in life.

Undead: Immune to mind-influencing effects, poison, sleep, paralysis, stunning, and disease. Not subject to critical hits, subdual damage, ability damage, energy drain, or death from massive damage.

Spell Immunity (Ex): The only spells that can affect will-o'-wisps are magic circle against chaos, magic circle against evil, magic missile, maze, protection from chaos, and protection from evil.

Natural Invisibility (Ex): A startled or frightened will-o'-wisp can extinguish its glow, effectively becoming invisible as the spell.

Breath Weapon (Su): Cone of cold, 15 ft., every 1d4 rounds; damage 4d6, Reflex half DC 16. Winter wolves can use their breath weapon while biting.

Trip (Ex): A winter wolf that hits with a bite attack can attempt to trip the opponent as a free action without making a touch attack or provoking an attack of opportunity. If the attempt fails, the opponent cannot react to trip the winter wolf.

Cold Subtype: Cold immunity; double damage from fire except on a successful save.

Trip (Ex): A worg that hits with a bite attack can attempt to trip the opponent as a free action without making a touch attack or provoking an attack of opportunity. If the attempt fails, the opponent cannot react to trip the worg.

Constitution Drain (Su): Living creatures hit by a wraith's incorporeal touch attack must succeed at a Fortitude save (DC 14) or suffer 1d6 points of permanent Constitution drain.

Create Spawn (Su): Any humanoid slain by a wraith becomes a wight in 1d4 rounds. Spawn are under the command of the wraith that created them and remain enslaved until its death. They do not possess any of the abilities they had in life.

Unnatural Aura (Su): Both wild and domesticated animals can sense the unnatural presence of a wraith at a distance of 30 feet. They will not willingly approach nearer than that and panic if forced to do so; they remain panicked as long as they are within that range.

Undead: Immune to mind-influencing effects, poison, sleep, paralysis, stunning, and disease. Not subject to critical hits, subdual damage, ability damage, energy drain, or death from massive damage.

Incorporeal: Can be harmed only by other incorporeal creatures, +1 or better magic weapons, or magic, with a 50% chance to ignore any damage from a corporeal source. Can pass through solid objects at will, and own attacks pass through armor. Always moves silently.

Daylight Powerlessness (Ex): Wraiths are utterly powerless in natural sunlight (not merely a daylight spell) and flee from it.

Poison (Ex): Sting, Fortitude save (DC 17); initial and secondary damage 2d6 temporary Constitution.

Improved Grab (Ex): To use this ability, the wyvern must hit with both claw attacks. If it gets a hold, it hangs on and stings.

Snatch (Ex): If a wyvern gets a hold on a creature four or more sizes smaller, it automatically deals damage with both claws and its sting attacks each round the hold is maintained. The wyvern can drop a creature it has snatched as a free action or use a standard action to fling it aside. A flung creature travels 30 feet and takes 3d6 points of damage. If the wyvern flings it while flying, the creature suffers this amount or falling damage, whichever is greater.