Spawned by the violent deaths of travelers in remote locations, black shucks are hound-like creatures that prowl the wilderness of the mortal world, marking those that are doomed to die in the wild. A black shuck is naturally invisible, though it can reveal itself to one individual at a time in order to seal that unfortunate's fate through the use of its baleful gaze.

A black shuck is driven to seek out those already at risk of violent death, usually travelers in dangerous areas. It chooses a single target from all potential victims and attempts to seal that target's fate with its gaze attack. The black shuck avoids killing its target outright, appearing just long enough to weaken its target and then retreating, leaving the victim to die at the hands of other nearby perils. Whenever possible, the black shuck avoids forms of confrontation more direct than its gaze attack.

Though a black shuck's role as a harbinger and agent of death is often viewed in a negative light, a black shuck is neither evil nor sadistic. To a black shuck, death is merely a journey that all mortals make; there is nothing cruel about ushering travelers further along the path when the risks they take have already pointed them in the right direction.

Undeath is a harder subject for black shucks. Some conclude that the undead have already experienced death, and have thus completed the most important part of their journey. Others feel that the undead have instead inverted death, and must be destroyed. Accordingly, a given black shuck may be either indifferent to the undead, or driven destroy them.

Gwyllgi (CR 5) A gwyllgi is a visible black shuck that seals its victim's fate with its baleful breath. It loses the black shuck's gaze and selective invisibility, but gains a breath weapon (15-ft. cone, 1d3 Con damage, Reflex DC 16 negates, usable every 1d4 rounds) and displacement (CL 5th) as a constant spell-like ability. It's displacement ability shifts its apparent location from side to side so rapidly, the gwillgi often appears to be three overlapping images of itself.