Tymher-haid

Mighty, wicked beings sometimes rise after death as wights, spectres or ghosts. Lesser and less evil creatures usually rest quietly, but when many of them die together in one place and never receive proper burial rites, they can return as a single, extremely minor undead called a tymher-haid, or ghost-swarm.

The swarm looks like a loose drifting cloud of tiny sparks in every color, a glorious light show hanging in the air. The beauty is a lure. Its brightest displays happen when it attacks: each spark brightens and intensifies as it accelerates toward a target, delivers its little burn, and fades back to its usual glow. To a bystander, the shifting kaleidoscope is lovely to watch.

The ghost-swarm dives on its victim like angry wasps. Each spark's sting is worth a mere 0.1 point of damage, yet up to a hundred strike each round, and that eventually kills almost anything that is not fire resistant.

For game purposes the swarm fights as one creature. Divide the number of sparks by 10, rounding down, to get its effective Hit Dice, so 52 sparks attack as a 5 HD monster and 49 as a 4 HD one. Since it strikes from every direction, the target loses shield and Dexterity bonuses to armor class, and the tiny attackers gain +2 to hit. A successful hit deals damage equal to the swarm's effective Hit Dice. Below 10 sparks a hit deals less than a point, so the swarm is no longer a real danger, though it can still disrupt spellcasting.

Each spark is nearly mindless, so tactics are crude. Only 20% of the time does it split its attacks among several targets, and it usually finishes one creature before moving on. It does not care what it kills: people, mounts, pack animals, birds in a nearby tree or a passing cloud of insects are all fair game, and the most noticeable creature, whether by size, movement or noise, tends to be next. That same mindlessness makes it immune to most psionics and illusions, because their effect is spread thinly over every spark.

Every spark has just 1 hit point, but they are tiny and nimble, so normal weapons have trouble hitting them. Fire cannot hurt them, while water is deadly. A flask of water flung into the swarm destroys 1d6 sparks and holy water twice that, and create water wipes out 2d10 sparks per caster level. Protection from evil holds the swarm off, and raise dead destroys it outright. It is turned as a skeleton, which is easy, but turning normally affects only 2d6 sparks, so it may not help much.

Whatever they were in life, the sparks now know no language. A crude telepathy links them, passing only basic commands such as 'target' or 'threat here'. Probing a single spark with mind-reading reveals nothing, and the whole swarm shows only the faintest flicker of thought.

The swarm needs no food and takes no pleasure in killing. It behaves less like a ghoul or wraith and more like an indifferent force of nature such as wind or rain. Should two swarms ever meet, they fuse and act as one entity from then on.

Ghost-swarms arise naturally but seldom, in places of slaughter such as plundered dungeons and blood-soaked battlefields. They appear only long after the dead are forgotten, sometimes years later. Water is such a threat that most do not last long, and an ordinary rainstorm is likelier to end one than adventurers are, so swarms rarely stray far from where they formed.

Because the raw material is so plentiful, several evil necromancers have tried to devise magic to raise or command one. Animate dead cast at a mass grave produces only zombies and skeletons, not sparks. Control undead governs just six sparks at a time, which is next to useless. Only the most single-minded necromancer would spend years on such research.