Thousands of tiny bones coalesce into a humanoid form only to disperse in a clattering swarm the next moment.
Bone Collective CR 11
Speed 30 ft.
Melee claw +19 (1d6 plus poison) or swarm (4d6 plus poison and distraction)
Space 5 ft. (10 ft. as swarm); Reach 5 ft. (0 ft. as swarm)
Special Attacks distraction (DC 22), sneak attack +9d6, superior disarm
Before Combat Bone collectives prefer to spy and skulk but if cornered fight without fear or hesitation, seeking to strip the flesh from their foes.
Morale If a bone collectives hit points fall below 18, their hive mind disappears and the remaining posthumes fall apart, scattering in all directions to find another collective.
Str 10, Dex 20, Con —, Int 14, Wis 10, Cha 16
Base Atk +13; CMB +12 (+18 disarm); CMD 27 (29 vs. disarm)
Feats Combat Expertise, Command Undead B, Dodge, Greater Disarm, Improved Disarm, Improved Initiative, Skill Focus (Perception), Skill Focus (Stealth), Toughness, Weapon Finesse
Skills Climb +7, Disguise +24, Intimidate +24, Knowledge (arcane) +10, Knowledge (religion) +10, Perception +27, Sleight of Hand +15, Stealth +36, Use Magic Device +13
SQ alternate form, hive mind
A bone collective can act as a swarm (composed of dozens of posthumes), or it can grant a single member (called an exarch) control, acting as a singular creature. Changing between forms is a swift action. In its non-swarm form, the collective can no longer use swarm attacks, but it can use sneak attack, disarm, and spellcasting, if it has caster levels. It can use its skills normally in either form.
All posthumes of a bone collective within 50 miles of their main body constantly communicate. If one is aware of a particular danger, they all are. No posthume in a group is considered flanked unless all of them are. Any bone collective with at least 1 hp/HD (or 18 hp for a standard collective) forms a hive mind, giving it an Intelligence of 14. (This is an exception to the usual swarm rules.) When a collective goes below this hp threshold, it becomes mindless.
Bone collectives distill minerals and cave dragon blood with elements of deadmind poison to create a reddish toxin, called wyrmblood venom, which they smear on their fangs. The resulting freakish red mouths on tiny skeletons are somewhat disturbing, and the effect of the toxin is deadly.
With their dozens of tiny fingers, bone collectives are exceptionally adept at grabbing or turning aside a weapon and disarming foes. They gain a +2 bonus to any disarm attempt and always wind up with a foe’s weapon in their hands if they succeed.
Organization solitary, pair, or hive (2–6)
Bone collectives’ tiny bones rustle when they move, as quiet as moving sand. Their long finger bones and hooked claws help them climb on their zombie mounts and control them. Bone collectives almost always wear robes or cloaks, the better to pretend to be humanoid. They understand that most creatures find their natures disturbing.
Bone collectives exist in numbers too small to have a proper society. They tend to latch onto the societies around them, whether human, goblin, or ghoul. They prey on the living and the dead, using and discarding them when no longer useful and replenishing lost component bones. They follow goals of their own, unrelated to other creatures alive or dead. The only exceptions are their interactions with necromancers, some vampires, and liches, all of whom they may serve and obey.
Bone collectives live in most environments, but they dislike extreme heat, as it makes their bones brittle.