Boneclaw

''This large skeletal humanoid's clawlike fingers are at least two feet long. Worse, the slender, knife-sharp claws contract and extend in length from moment to moment, sometimes instantly reaching a length of 10 or more feet, before slowly contracting.''

Features
Boneclaws resemble humanoids with the flesh half-flayed off, or perhaps with flesh grafted onto roughly half of a large humanoid skeleton. Each of a boneclaw's three long digits ends in a thin claw which can be used to alternatingly slash and impale victims.

Boneclaws are strong and fast, and moderately intelligent. They take great pleasure in inflicting pain on the living, and enjoy toying with their prey by tearing them apart when they try to flee. At close range they can extend their claws to lengths of ten or fifteen feet in the blink of any eye.

Origin
The original boneclaws were created as instruments of butchery by deathpriests of Orcus from the remains of an ogre tribe that worshipped that demon lord. The bones of ogres were combined with warped souls of oni to create a sadistic monstrosity. The ritual used to create boneclaws has since spread through shadowy networks, and now uses a wide range of materials, and the creatures themselves have in many cases set out to freely roam the planes in search of prey.

One dark ritualist in the gate-town of Torch who abducted dozens of travelers in a bid to purchase the magic required to create boneclaws of his own. The shadow demons who bought his slaves did sell him the ritual, but he was eventually devoured by his own errant creations.