These noisome demons are made solely from blood. They are not flesh like men, instead they are beings of the warm clotted blood used in their foul summoning ritual, bound together by unwholesome sorcery and their own maleficent will.
Only found guarding the darkest sanctums and in the service of the most powerful practitioners of the dark arts, they are found lurking near the pools from which they were raised. Some surmise they are linked to the blood source of their creation.
The gaze of their empty eye sockets is unnerving, their glistening skin gently throbs and drips of blood fall continuously from their rictus grins, but it is the flopping vestigial proboscises under its arms that horrify. They writhe seeking fresh sources of blood and should a blood defiler envelop a victim in its arms these appendages burrow into the host and greedily pump blood from their screaming prey.
The blood used in their creation directly affects the blood defilers power. Sorcerers are careful to use pure and innocent blood in their creation for tainted blood diminishes their control over the abominations. Tainted blood and tainted blood defilers can turn on their creators or run amok, killing all in their reach in a frenzy of teeth, claws and blood spray.