Ungulosin

The ungulosin is a guardian spirit native to the Elemental Plane of Water with no flesh of its own. To act, it gathers schools of fish, eels, octopi and similar sea life and moves them in perfect unison as a single body. The animals cannot resist, though in truth they do not want to: the spirit never mistreats them, and they come to no harm unless it is attacked.

Its body is always at least 15 feet long and assembled only from Tiny or Small sea creatures of no more than animal Intelligence, so it never uses sharks or giant sea beasts, though it may borrow hundreds of little ones. The usual shapes are an eel or a big hunting fish, but many like a form echoing their components, so a swarm of squid might move as one gigantic squid.

Whatever its shape, every ungulosin has the same abilities, including a head with a wide mouth crowded with dagger-sharp teeth. The bite deals 1d4+4 damage and injects venom. A failed save vs. poison means 1d4 rounds of paralysis followed by spasms that deal 1d6 damage per round until death. A successful save means no paralysis and no poison damage.

Its swarm body makes it maddening to fight. The creatures strike as one being but take harm as many, and any physical attack, melee or missile, can only ever hit a single animal. For the spirit, that means a hit deals 1 point of damage or nothing. The simple way to decide is to roll any die: even means 1 point, odd means none. The harsher, more realistic way compares the damage to the average hit points of the component animals. If it would kill one, the ungulosin loses 1 point; otherwise nothing. Built from weed eels (1-1 HD, about 3 hp each), it ignores hits of 1 or 2 points, while a hit of 3 or more, even 30, still costs it only 1.

Spells do much better. Area effects harm it normally, but single-target damage spells such as magic missile or acid arrow suffer the same limit as weapons. It is immune to sleep, hold and charm effects. When it is slain or banished, the animals break apart and scatter in confusion.

Ungulosins live alone and stand outside the Water plane's order. No power, prince or elemental lord commands their loyalty. Each roams the plane's boundless sea following its own aims, attacking some beings (often but not always outsiders), helping others and altering things as it pleases. Like a water elemental it is a spirit that dons a body suited to its task, but it is a free agent.

Rarely, one leaves its plane to guard a lonely lake or stream elsewhere, often for no obvious reason. There it may cooperate or clash with nereids and other local water spirits.

Being a spirit, it neither eats, sleeps nor breeds, and the animals in its body need no food or rest while under its control.

Legend holds that ungulosins began as air spirits betrayed by a sky power. In bitter disappointment they left the Elemental Plane of Air together and settled in Earth for ages, but found it too slow and changeless to bear. A briefer stay in Fire ended because its inhabitants were too hostile and strange. At last they reached Water, which reminded them of home: always moving and changing, yet nurturing rather than hostile. They have lived there so long that most think them natives, unaware of their dark wanderings.