| Hit Dice: | 11d6+3 (41 hp) |
| Initiative: | +6 |
| Speed: | 5 ft. (1 square), fly 50 ft. (perfect) |
| Armor Class: | 24 (+8 size, +6 Dex), touch 24, flat-footed 18 |
| Base Attack/Grapple: | +5/— |
| Attack: | Swarm (3d6) |
| Full Attack: | Swarm (3d6) |
| Space/Reach: | 10 ft./0 ft. |
| Special Attacks: | Dazzling illumination, distraction (DC 15) |
| Special Qualities: | Hive mind, immune to weapon damage, low-light vision, swarm traits |
| Saves: | Fort +5, Ref +15, Will +11 |
| Abilities: | Str 1, Dex 22, Con 11, Int 7, Wis 15, Cha 18 |
| Skills: | Diplomacy +6, Hide +36, Listen +16, Move Silently +13, Sense Motive +9, Spot +16 |
| Feats: | Great Fortitude, Iron Will, Lightning Reflexes, Toughness |
| Environment: | Temperate forests |
| Organization: | Solitary, pack (2–4), or colony (5–8) |
| Challenge Rating: | 8 |
| Treasure: | None |
| Alignment: | Always chaotic neutral |
| Advancement: | — ♊ |
| Level Adjustment: | — |
You spy a naked and glowing elfin creature only 4 inches tall balancing on a leaf, and as you watch, it spreads dragonfly wings. Suddenly thousands of these glowing fey fly up from nearby hiding spots, filling the air with a deep drone and a cacophony of high-pitched voices. They form a multihued cloud of light that surges toward you.
Shimmerlings are minuscule and nearly mindless fey that feed on pollen. Individually harmless, shimmerlings would be no more worrisome than sparrows but for their ability to swarm.
Shimmerlings form swarms when under great stress. Common triggers are a lack of food sources, loss of habitat, or overhunting by predators. Shimmerlings collect into swarms primarily to move the entire population to another location, but a swarm also develops an aggressive group intelligence that often seeks revenge on whatever it thinks caused the stress.
An individual shimmerling looks like a 4-inch tall elf with dragonfly wings. Its skin and hair are the same color as the glow it gives off, which can be any color of the rainbow. A shimmerling weighs 1 ounce.
Shimmerlings speak Sylvan.
A shimmerling swarm often flies around out of reach of foes to hypnotize them before singling out one to surround and attack. A shimmerling swarm deals 3d6 points of damage to any creature whose space it occupies at the end of its move.
Dazzling Illumination (Su): Each shimmerling in a shimmerling swarm glows in some color of the rainbow. When the members of a swarm concentrate this glow, the swarm sheds light equivalent to a daylight spell. This illumination dazzles any sighted creature within a 60-foot radius that has its eyes open, whether or not it is looking at the shimmerling swarm.
Furthermore, the swarm’s display of light and movement is hypnotic. At the mere sight of an illuminated shimmerling swarm, a creature within 300 feet must succeed on a DC 19 Will save or be fascinated for as long as the swarm is in sight. Any potential threat allows another saving throw against the effect, and an obvious threat automatically frees the creature from the effect, as does vigorous shaking. A creature that succeeds on the saving throw is immune to that shimmerling swarm’s hypnotic form for 1 minute. This is a mind-affecting ability. The save DC is Charisma-based.
A shimmerling swarm can activate or deactivate its dazzling illumination as a standard action. It cannot hide (automatically fails Hide checks) while shedding dazzling illumination.
Hive Mind (Ex): A shimmerling swarm that has at least 1 hit point per Hit Die (or 11 points for a standard shimmerling swarm) forms a hive mind, giving it an Intelligence score of 7. When a shimmerling swarm is reduced below this hit point threshold, its Intelligence score is reduced to 1. This change reduces its skill modifiers to the following values: Diplomacy +4, Hide +36, Listen +2, Move Silently +6, Sense Motive +2, Spot +2.
Source: Monster Manual III, page 152.