Hemic Swarm

Diminutive Outsider (Swarm) [Ritual]
Hit Dice: 12d8+39 (93 hp)
Initiative: +10
Speed: 5 ft. (1 square), fly 40 ft. (Good)
Armour Class: 20 (+4 size, +6 Dex), touch 20, flat-footed 14
Base Attack/Grapple: +12/-
Attack: Swarm (3d6)
Full Attack: Swarm (3d6)
Space/Reach: 10 ft./0 ft.
Special Attacks: Distraction, Blood Drain
Special Qualities: Damage reduction 10/magic, darkvision 60 ft., immune to weapon damage, swarm traits, split swarm
Saves: Fortitude +11, Reflex +14, Will +11
Abilities: Str 1, Dex 22, Con 16, Int 6, Wis 13, Cha 9
Skills: Hide +19, Listen +10, Spot +10
Feats: Alertness, Improved Initiative, Iron Will, Toughness
Environment: Areas of great bloodshed
Organization: Solitary, fright (2–4 swarms), or terror (5–8 swarms)
Challenge Rating: 8
Treasure: None
Alignment: Always neutral evil
Advancement: 13-24 (Diminutive)

A hemic swarm is comprised of thousands of small but unnaturally intelligent and cruel droplets of blood that feast upon any whom they run across. Swarming across their foes, all that is left behind is the dessicated husks of ruined creatures.

Combat
Like any swarm, a hemic swarm seeks to surround and attack any living prey it encounters. A swarm deals 3d6 points of damage to any creature whose space it occupies at the end of its move. The swarm siphons life out of the bodies of those they feast upon, gaining strength from the effect.
A hemic swarm’s attack is treated as an evil-aligned weapon and a magic weapon for the purpose of overcoming damage reduction.

Distraction (Ex): Any living creature that begins its turn with a hemic swarm in its space must succeed on a DC 18 Fortitude save or be nauseated for 1 round. The save DC is constitution-based.
Blood Drain (Ex): Any living creature that the hemic swarm damages takes 1d2 points of constitution damage. For every eight points of constitution damage dealt, the hemic swarm advances by a single hit dice.
Split Swarm (Ex): Once a swarm has gained enough hit dice to have a total of 18 or more, it can split into two equal sized swarms, each with hit dice equal to one half (rounded down) of the original, larger swarm. These swarms are free-willed independent creatures and generally go their own separate ways.