Nightwalker (Dungeons & Dragons)

Nightwalkers are evil undead monsters from the roleplaying game Dungeons & Dragons. Native to the Shadowfell, these entities are very dangerous and deadly to any living creatures. Utterly malicious, Nightwalkers seek out living beings to inflict pain and misery upon them, taking pleasure in the suffering of their victims.

Physiology
A Nightwalker is tall and skinny with an anti-life aura trailing behind it. It has blue eyes with three white dots inside them. It has five sharp claws on each hand and ebony skin. Lastly, it sports a pair of horns sprouting from its head which can vary in size, appearing as minute points or long and curved like those of a ram. Despite its skinny frame, a Nightwalker has strong muscles and great strength.

Abilities
A Nightwalker is a being of anti-life, enabling it to severely damage foes merely by proximity. It can also attack with its claws (which are fused with necrotic power) or destroy living creatures with its aura of death. Nightwalkers can also absorb the life-force of the slain creatures.

Life cycle
Nightwalkers are born when rituals to enter or harness the Negative Plane fail. The spellcasters are trapped in it, and if they are not prepared die from exposure to the plane. A Nightwalker replaces this creature and proceeds to destroy anything related to the spellcaster. For the trapped creature to escape, the Nightwalker must be lured back into the horrid world. Destroying the beast dooms the spellcaster to death.