Nentruhn

From the realm of the void, many twisted, reality-defying aberrations have spawned, commonly known as void-sent. Among these is a powerful creature that exists on the same level as the gods themselves. It is commonly known by the name Nentruhn, an evil creature that seems to have a singular desire to collect all that can be known in the many realms. To house all of this knowledge, Nentruhn has stabilized one of the deepest sections of the abyss to create its realm; a maze of twisting and warping passages and hallways filled with books and scrolls and all manner of containers that can house knowledge.   To expand its domain, Nentruhn often creates relics bearing its power and manifests them in one of the inhabited realms. The voidsent relies on a creature being drawn to the item. Whenever a creature is foolish enough to interact with it, their mind will often fall under the control of Nentruhn, who steals all their knowledge. What remains of the creatures is commanded by Nentruhn to try and get others to interact with the item. These items, also known as beacons of Nentruhn have the additional effect that they attract voidsent from nearby sections of the void.
As a result of these beacons existing, a small number of cults have popped up in the ethereal plane. These cults worship Nentruhn, commonly believing that the beacons would allow them access to Nentruhn’s realm, which contains vast amounts of knowledge. It is this knowledge that usually motivated cultists due to the power that can be obtained with it.