Grendelboks are one of the many goblinoid races, and look a little bit like goblins themselves, when they can be seen at all - they have short, gaunt frames and wide heads with prominent pointy ears around a mouth of sharp yellow teeth. Their eyes are large and milky, and can shine faintly in the darkness when fully open. What makes them different from other goblin races is their bone structure, in that they don't have one.

These creatures evolved in natural cavern systems and the many narrow cracks and crawlways deep in the bowels of the earth, but rather than tunnelling out homes for themselves they adapted to fit their environment. Their "bones" are in fact rubbery cartilage, allowing them to distort their shape to fit through almost any narrow space or hide in tiny shadows.

An adult Grendelbok can squeeze through an opening no wider than the side of a human's hand or large-ish keyholes and cling underneath tables, invisible even in that faint shadow. Their brown-grey mottled hide makes it even easier for them to vanish, and their flexibility allows them to hide instantly. Ten Grendelboks could be in a normal tavern taproom and nobody would know.

Another feature of their stygian adaptation is that they can hold their breath for hours or even days on end, travelling underwater with all the speed and considerably more agility than a fish. Their hard chitinous nails allow them to find purchase on almost any solid surface, even slippery or muddy ones, so they are able to climb like spiders.

Although, like most goblin races, they are sensitive to light, especially sunlight, they have been employed by various dark forces as spies, scouts, and saboteurs, as well as being notably effective assassins. They aren't terribly intelligent for the most part so simple instructions are best, but they can relay back troop numbers or drop a potion into a well with great ease.

Since their hearing is superb, their masters have often trained them to hunt targets based on the sound of that individual's voice, even if it's at a parley across a battlefield or atop distant castle walls.

Salt will affect a Grendelbok in the same way as it does a slug, scalding and burning their skin, and for some reason they despise ferrets, anmosity which goes both ways. A ferret will become very aggressive when a Grendelbok is near, and will sniff it out very quickly, attacking ferociously.

In combat, Grendelboks prefer hit and run tactics and small, poisoned implements like daggers, blowguns and shortswords. They rarely wear armour or many clothes beyond a loincloth - equipment is hung on cords over their shoulders - but they do have a great love for silver, and will pilfer silverware even when they're meant to be doing something else. Finding a stash of silver is usually a good sign that a Grendelbok is near.