Shadow Creature

Shadow creatures dwell on the Plane of Shadow, sometimes crossing into other planes where the barriers between dimensions are weak. Just as parts of the Plane of Shadow resemble a strange, distorted version of the Material Plane, shadow creatures superficially resemble creatures from the Material Plane. Shadow creatures are darker, more elusive, and spookier than their material counterparts.
Shadow creatures are not to be confused with shadows (undead creatures that dwell on the Plane of Shadow). Other creatures native to the Plane of Shadow exist that have stronger or weaker connections to the energies of that place (such as the shadow mastiff) and therefore do not follow this template. 5th Edition

Creating a Shadow Creature

"Shadow" is a tempalte that can be added to any corporeal Aberration, Animal, Fey, Giant, Humanoid, Magical Beast, Monstrous Humanoid, Plant, or Undead.
A shadow creature uses the base creature's statistics and abilities except as noted here. Do not recalculate the creature's Hit Dice if its type changes.
Size and Type: Animals with this template become Magical Beasts, but otherwise creature type is unchanged. Shadow creatures encountered on the Material Plane have the Extraplanar Subtype and are native to the Plane of Shadow.
Speed: As base creature +20 ft.
Special Qualities: A shadow creature retains all the special qualities of the base creature and also gains the following:

• A Shadow creature has Resistance 5 + 1 per Hit Die to Cold damage, to a maximum of 15.
• A Shadow creature has Darkvision.

Shadow Blend: So long as a Shadow creature is not in direct sunlight, it can disappear into the shadows, giving it total concealment. Artificial illumination does not negate this ability, but a Daylight spell will.
Shadow creatures also have one extra ability for every 4 Hit Dice they possess (minimum of one additional ability) chosen from the following list:

• Constant Withstand spell. Once used, it returns after 1 minute.
• The Shadow creature can cast Cause Fear as an innate spell, requiring no material components. Charisma is its spellcasting modifier. Once cast in this way, the Shadow creature cannot cast it again in this way until it finishes a long rest.
• The Shadow creature regains 2 hit points at the beginning of each of its turns so long as it has at least 1 hit point. If the Shadow creature takes radiant damage, this regeneration does not function at the beginning of its next turn.
• When an effect allows the Shadow creature to make a Dexterity saving throw to take only half damage, it takes no damage on a success, and half damage on a failure.
• The Shadow creature can cast Mirror Image as an innate spell, requiring no material components. Charisma is its spellcasting modifier. Once cast in this way, the Shadow creature cannot cast it again in this way until it finishes a long rest.
• The Shadow creature can cast Plane Shift as an innate spell, requiring no material components. Charisma is its spellcasting modifier. When cast in this way, it can only go to or from the Plane of Shadow. Once cast in this way, the Shadow creature cannot cast it again in this way until it finishes a long rest.

Proficiencies: Shadow creatures gain Proficiency in Stealth, or Expertise if they are already Proficient.
Challenge Rating: Same as base creature +1.
Alignment: Usually Neutral Evil.

3.5th Edition

Creating A Shadow Creature

"Shadow" is a template that can be added to any corporeal aberration, animal, dragon, fey, giant, humanoid, magical beast, monstrous humanoid, plant, undead, or vermin (referred to hereafter as the base creature).
A shadow creature uses all the base creature's statistics and abilities except as noted here. Do not recalculate the creature's Hit Dice, base attack bonus, saves, or skill points if its type changes.
Size and Type: Animals or vermin with this template become magical beasts, but otherwise the creature type is unchanged. Shadow creatures encountered on the Material Plane have the extraplanar subtype and are native to the Plane of Shadow.
Speed: As base creature x 1-1/2.
Special Qualities: A shadow creature retains all the special qualities of the base creature, and also gains the following:

• Resistance to cold equal to 5 + 1 per Hit Die, to a maximum of 15.
• Darkvision out to 60 feet.
• Low-light vision.

Shadow Blend (Su): In any conditions other than full daylight, a shadow creature can disappear into the shadows, giving it total concealment. Artificial illumination, even a light or continual flame spell, does not negate this ability, but a daylight spell will.
Shadow creatures also have one additional special ability for every 4 Hit Dice they possess (minimum of one additional ability) chosen from the following list:

• +2 luck bonus on all saving throws.
• Cause Fear (Sp): 1/day. Caster level 5th. The save DC is Charisma-based.
• Damage reduction 5/magic.
• Evasion, as the rogue class feature.
• Fast healing 2.
• Mirror Image (Sp): 1/day. Caster level 5th.
• Plane Shift (Sp): 1/day, to or from the Plane of Shadow only. Caster level 15th.

If the base creature already has one or more of these special qualities, use the better value.
Skills: Same as base creature. Shadow creatures gain a +6 racial bonus on Move Silently checks.
Feats: Same as the base creature.
Environment: Plane of Shadow
Organization: Same as the base creature.
Challenge Rating: Same as the base creature +1.
Treasure: Same as the base creature.
Alignment: Usually neutral evil.
Advancement: Same as the base creature.
Level Adjustment: Same as base creature +2.