Water Weird
Creature
The Water Weird is a malevolent spirit that animates a body of still water - a pool, a cistern, a fountain in some flooded ruin - lying invisible within it until something living comes to drink or to cross. Then it rises as a striking serpent of water, lashing out to seize its prey and drag it down into the pool to drown. Cut it apart and it simply collapses back into the water, to reform a moment later; the only sure end is to befoul or drain the water it inhabits. Many a thirsty traveller has met one at exactly the wrong moment.