Vacuous Moon

A grim curse, an unnatural celestial phenomenon descending upon the world—the Vacuous Moon. Resembling naught but a gaping maw of shadows, it swallows all light, casting the land into an all-consuming darkness. This sinister moon, akin to a black hole in the firmament, brings forth terrors from beyond the veil, revealing a realm of spectral agony visible only to those with the dread fortune of perceiving the ethereal. In this adjacent plane, ghastly spirits writhe in torment, suspended upside down by iron chains that ensnare their necks. Their frightful visages, twisted by suffering, emit harrowing wails that rend the air, filling the hearts of those who bear witness with dread.
When the Vacuous Moon is visible, the following effects apply to the world.

Monsters

Monsters of CR 5 or lower are blinded.

Monsters gain blindsight out to 30 feet.

Monsters have advantage on Perception checks that rely on hearing or smell.

Monstrosities gain the following trait:

**Void Step:** After the monster is damaged by a ranged attack, it can use its reaction to teleport to an empty space within 5 feet of the attacker and make a single melee weapon attack against it.

Travel

The world is engulfed in the darkness of the Vacuous Moon. The light of torches barely illuminates the filth-ridden streets, and screams of madness echo through the night as the void weakens the barrier between the afterlife and reality.

Staring into the Abyss

If a character looks directly at the moon for more than 6 seconds, they are faced with the depths of the abyss, which gazes back at them. They must succeed on a Wisdom saving throw against the Madness DC or gain a short-term madness. The first time in a day that a character gains the ability to see invisible creatures or objects (such as the see invisibility spell or with truesight), they are compelled to stare at the moon for a round.

Vacuous Light

The void absorbs all light:

Darkvision doesn’t function.

Dim light becomes darkness.

A creature that can see invisible creatures and objects doesn’t suffer disadvantage on perception checks due to darkness.

Creatures have disadvantage on saving throws against madness while not in bright light.

Madness

The madness section of each moon refers to a Madness DC, which is indicated in the following table.

Average Party Level

Madness DC

1-4

11

5-8

13

9-12

15

13-16

17

17-20

19

21+

21

The void wears a heavy toll on the mind. Whenever a character fails a Wisdom saving throw, they gain one short-term madness (saving throws against madness do not trigger this effect).

Short-Term

Whenever a character gains a short-term madness under the Vacuous Moon, they see their regrets and sorrows take life. They are under the effect of the see invisibility spell for the duration of the madness. The effects of the spell cause them to see the shadowy figures of all the loved ones they lost, hanging upside down, chains wrapped around their neck, floating towards the moon. Observing that which should be reserved to the dead shatters one’s psyche; they become frightened for the duration of the madness.

Long-Term

Whenever a character gains a long-term madness under the Vacuous Moon, the shadows they saw previously now become as clear as day, an image indistinguishable from reality. They are under the effect of the see invisibility spell and have disadvantage on all attack rolls, as they lose the ability to differentiate between reality and the beyond for the duration of the madness. A blinded creature doesn’t suffer from this effect.

Indefinite

A character that gains an indefinite madness under the Vacuous Moon loses their grip on reality.
Roll a d100;

on a result of 33 or lower, the character becomes part of the void, and is able to cast the blink spell on itself at will, without providing components, shifting between planes of existence. If they use the spell 3 times in a day, when the spell ends, the character comes back into reality without their eyes and becomes permanently blinded.

On a result of 34 or higher, figures of their past rip out the character’s eyes before vanishing into the void with them, leaving the character permanently blinded.

Type

Metaphysical, Supernatural