Hivebrood

A hivebrood is an ant-like colony of large insects with a horrible difference: its members are parasites that seize other beings, control them and eventually consume them. Individuals mean nothing; only the hive matters. Five castes do its work: broodlings, soldiers, lieutenants, mothers and controllers. The colony also holds larvae, legless grubs about 6 inches long, helpless (AC 10, 1 hit point) and unable to move or fight. Hive members place larvae on paralyzed humanoids; each grub latches onto the nape, chews into the spine and starts remaking the host's body. All members reek of sickly sweet chemicals and clack their mandibles wetly; broodlings imitate the noise with their host's teeth.

Broodlings, the weakest mobile caste, are hosts taken by larvae, marked by fibrous films over the eyes, chitinous skin and an eerie insect gait. In time they mature into soldiers, and these two castes are the most numerous. Soldiers keep a humanoid outline but sprout antennae and faceted eyes inside a tough shell. Lieutenants are larger, stronger, smarter soldiers that lead the rest. Mothers and controllers have bloated, sack-like bodies and insect faces and can barely move, though controllers can claw and bite. The controller, also known as the hivemind, feeds abilities and knowledge to the lower castes and coordinates the colony, while the mother exists only to breed.

Hivebrood fight without fear, directed by controllers who will spend any resource for the hive's advantage. They sense foes by touch and smell, so darkness is no hindrance and spells like darkness do nothing, though darkness paired with silence confuses them enough for a -2 to all their attacks. Fire and heat deal them double damage.

Broodlings, still changing, fight poorly with budding claws and bite, or bite plus a weapon, usually an axe or spear. Soldiers, the true workforce, attack the same way, but their gluey bite paralyzes for 2d8 turns unless the victim saves vs. poison, or until haste, cure serious wounds or neutralize poison releases them; they rarely kill the paralyzed, hauling them home as hosts instead. Lieutenants run squads of soldiers with military precision through scent signals that reach 30 feet, and each can carry as many as five hivemind abilities for its troops. Mothers, the worst fighters, act only if the hive's core is threatened, spewing a noxious cloud 30 feet around themselves, at most three times daily; anyone inside must save vs. poison at -1 or take 3d6 per round until a save succeeds.

A controller gains every ability of creatures it eats, including better saving throws, and can broadcast them as airborne scent. After devouring, say, a 6th-level wizard and a 3rd-level thief, it could let the whole hive cast whatever the wizard had memorized at death or hide in shadows like the thief, so an entire colony might throw fireballs. Each ability counts as a single spell regardless of level, a thief skill, an attack rank, or a fighting option like parry, disarm, smash or multiple attacks.

The scent spreads only 60 feet each round and fades after three rounds, and recipients must use the ability within three rounds or lose it, except lieutenants, which store them. A controller can broadcast only one ability at a time per hive; a second scent sent before the first leaves the members' minds (six rounds) confuses them, leaving them able to defend but not attack. Scents from several controllers can be held together and used one at a time. A released ability is forgotten by the controller, which can otherwise retain any number, duplicates included. Each spell cast costs the caster 1 hit point, a price it will pay to the death for the hive.

The hive is a strict hierarchy in which each member does its job as well as it can. Its single mother is queen and living heart, nearly immobile and guarded fanatically. Besides laying eggs, she secretes a pungent, chemical-rich jelly that turns chosen larvae into lieutenants and controllers. The controllers make most decisions, including when the mother should produce a new mother egg and where it should be carried, with an escort, to found another hive.