Fantasy Monster: Arc-Swarm

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Arc-Swarm

A cloud of amber shards flies through the air, electricity crackling around it.

CR 8; XP 4,800
N Fine Construct (swarm)
Init +0; Senses darkvision 60 ft., blindsense 120 ft. (energy); Perception +0

Defense
AC 18, touch 18, flat-footed 18 (+8 size)
hp 88 (16d10)
Fort +5; Ref +5; Will +5
Immune electricity, swarm traits, weapon damage

Offense
Speed fly 60 ft. (perfect)
Melee swarm (4d6)
Space 10 ft.; Reach 0 ft.
Special Attacks arcing charge (DC 18), building charge, distraction (DC 18)

Statistics
Str 1, Dex 10, Con —, Int —, Wis 11, Cha 1
Base Atk +16; CMB —; CMD —
Skills Fly +16

Ecology
Environment ruins, underground
Organization solitary, battery (2–8)
Treasure standard (amber shards and dust)

Special Abilities

Arcing Charge (Su) At the beginning of its turn, or when it is destroyed, arc-swarm releases the accumulated charges in a wild display of electricity, dealing 1d6 points of electric damage per charge consumed (2d6 per charge when destroyed) to all creatures within 40 feet spread. A successful Reflex saving throw (DC 18) halves the damage. In cold or colder environments, or if the arc-swarm was dealt cold damage within the last round the range of arcing charge extends to 60 feet. In hot or hotter environments, or if the arc-swarm was dealt fire damage within the last round, arcing charge deals 1d8 damage per charge consumed (2d8 per charge when destroyed). The saving throw DC is Constitution-based.

Building Charge (Su) An arc-swarm gains one charge for each creature it damages with its swarm-attack. It also gains a charge whenever it would be dealt electric damage or suffers any acid damage. When exposed to dust-storms, sandstorms, or rainstorms, or extreme winds, an arc-swarm gains 1d4–1 charges at the end of its turn.


Arc-swarms are formed out of amber shards imbued with the power of lightning. They are mindless but easily attracted to electricity, metal, movement, friction, and sources of energy, and are quickly agitated into drawing and discharging energy all around. They are especially dangerous in groups when their arcing charges chain-build charge in each other.