Initially, Bone Snatchers take the form of a recently drowned human, a pale and bloated corpse streaked and smeared with the ooze and muck of their watery domain. Over time the transformation turns any hair the creature once had greenish-gray. Their nails and teeth lengthen and transform into sharp claws, while the flesh of their hands and feet slowly shifts and transforms, becoming webbing between fingers and toes. Their skin slowly stretches tight over their skeletal form as the creature's flesh decays away, leaving them thin and pallid, little more than webbed skin stretched over a bony frame.
The final transformation occurs when a Bone Snatcher claims a victim. After consuming their flesh, the Snatcher incorporates the victim's bones into their own bodies, magically fusing their limbs and spine into two flexible tentacle-like arms ending in bony claws connected to Bone Snatcher's shoulders and back. The skull of each victim is mounted as a sort of trophy to the creature's chest or waist (though some say these skulls retain some form of consciousness). As additional victims are consumed existing limbs are extended or new limbs are created. There are stories of Bone Snatchers with a dozen or more tentacle-arms, each ten or twenty feet long.
Bone Snatchers hunt by lurking in the shallow waters of rivers near trails, bridges or fords. When they sense approaching prey they leap forth to seize their victim with sharp claws and fangs, then drag them beneath the water's surface to rend and tear flesh as the victim drowns. Bone Snatchers prefer to hunt under the cover of darkness, but have no fear of sunlight. They have the following characteristics:
- Great strength and toughness.
- Superb swimming ability.
- Good damage and accuracy with claws and fangs.
- Elemental resistance - The creature's watery form grants them a Fair resistance bonus to fire damage and a Good resistance bonus to cold damage.
- Watery regeneration - Bone Snatchers recover one rank of damage per hour when submerged in running water.
- Tentacle-arms - Each Bone Snatcher has 1d6-1 tentacle-arms which it uses in combat. Each arm has Good toughness and strikes with good damage and accuracy.
- Ambush - Bone Snatchers are cautious predators with a certain native cunning. When attacking from ambush they gain a Good bonus to all combat checks during the first three rounds of battle.
If submerged, a damaged Bone Snatcher will regenerate fully provided some portion of its original skull remains. Tentacle-arms do not regenerate so hit and run tactics may weaken a powerful creature. The only way to permanently lay a Bone Snatcher to rest is to burn their remains completely and scatter the ashes.