Lacuna

Lacunae are spirits of space and the offspring of the timeless Void.
Lacunae are utterly beyond the understanding of mortals and even worldly spirits. To look upon a lacuna's true form is to invite instant madness, as their bodies are said to not conform to known laws of perception. Both angels and demons claim allegiance to these spirits, the former claiming that one day the world will transcend all evil and the lacunae will emerge to uplift Creation to higher consciousness, and the latter claiming that after the Grand Annihilation, the world will be swallowed by the Void and its spirits will remake a more perfect reality.
What is known is that the lacunae of the Void are not intended to exist within the world in its current state - when one of these spirits emerges, be it at the summoning of warlocks or more often, at random and for no scrutible reason at all, chaos ensues, as their radically alien nature rips the fabric of Law around them. Functionally, it matters not whether their nature is one of infinitely higher order or infinitely lower chaos - they are not of this cosmos, and their bodies react with forceful hostility to its laws.
The appearance of a lacunae is sufficient to shatter the mind of a mortal which looks upon it, and so their visage is heavily speculated about. However, as the most enlightened (or perhaps endarkened) minds have glimpsed these spirits and survived to tell accurately, there are some accounts of their general forms. While the sacred magi who have seen a lacuna most frequently describe the being as a geometric form of impossible but pristine order, every angle and aspect containing the utmost perfection of creation, warlocks and certain other profane magicians describe tentacled, formless beings of amorphous protoplasm. Sages suggest that this may be indicative of the direction of Creation from the most primitive and base organisms to the most refined and redeemed specimens.