Lesser Shadow Swarm (CR 1)

scary shadow

Intended as an encounter for a 1st-level party, this creature is a mixture of the “Skiurid” from Monster Manual IV and Swarm traits.

A lesser shadow swarm appears as a small flickering area of darkness that moves quickly between poorly-illuminated areas.  It seeks to ambush other creatures in the darkest areas possible, where it can remain hidden while attacking.  It immediately flees if confronted by artificial illumination.

Lesser Shadow Swarm (CR 1)

Always NE Tiny magical beast (extraplanar)
Init +3; Senses darkvision 60 ft., low-light vision; Listen +3,
Spot +7

AC 15, touch 15, flat-footed 12 (+2 size, +3 Dex)
hp 2d8 (9 hp)
Fort +2, Ref +5, Will +1

Speed 20 ft. (4 squares), climb 20 ft.
Attack Swarm (1d6 plus distraction)
Full Attack Swarm (1d6 plus distraction)
Space 5 ft.; Reach 0 ft.
Base Atk +1; Grp –
Special Actions Expand

Abilities Str 3, Dex 17, Con 10, Int 2, Wis 12, Cha 12
Special Qualities Darkvision 60 ft., immune to weapon damage, swarm traits, tremorsense 30 ft., vermin traits
Feats Alertness, Weapon Finesse
Skills Balance +11, Climb +11, Hide +19, Listen +3, Move Silently +11, Spot +7

A lesser shadow swarm seeks to surround and attack any living prey it encounters. A swarm deals 1d6 points of damage to any creature whose space it occupies at the end of its move.

In order to attack, a single swarm moves into opponents’ spaces, which provokes an attack of opportunity. It can occupy the same space as a creature of any size, since it crawls all over its prey, but remains a creature with a 10-foot space. Swarms never make attacks of opportunity, but they can provoke attacks of opportunity.

Distraction (Ex)
Any living creature that begins its turn with a spider swarm in its space must succeed on a DC 11 Fortitude save or be shaken for 1 round. The save DC is Constitution-based.
(A shaken character takes a -2 penalty on attack rollssaving throwsskill checks, and ability checks.  Shaken is a less severe state of fear than frightened or panicked.)

Expand (Ex)
At the end of the swarm’s turn, if any creature has taken damage within its area, the swarm increases in size by one increment and gains one hit dice.  (For ease of bookkeeping, take the average roll for a d8: 4, 5, 4, 5, etc.)

The lesser shadow swarm has a +8 racial bonus on Balance, Climb, Hide, and Move Silently checks. A lesser shadow swarm can always choose to take 10 on Climb checks, even if rushed or threatened. It uses its Dexterity modifier instead of its Strength modifier for Climb checks.

Vulnerabilities Of Swarms

Swarms are extremely difficult to fight with physical attacks. However, they have a few special vulnerabilities, as follows:

A lit torch swung as an improvised weapon deals 1d3 points of fire damage per hit.
A weapon with a special ability such as flaming or frost deals its full energy damage with each hit, even if the weapon’s normal damage can’t affect the swarm.
A lit lantern can be used as a thrown weapon, dealing 1d4 points of fire damage to all creatures in squares adjacent to where it breaks.