Shadows

"Shortly after the Long Night started the Shadows came, slaying everything in their path, only people in remote parts of the world had any chance of survival" - Modern History, by Marcus Landry 625 AR

The shadows are a class of amorphous creatures of various sizes and power. First seen during the reckoning Shadows continue to be an existential threat to civilization. They start as blob like Shadowspawn and can grow to huge, powerful and semisolid form of Greater Shadows.
Shadows can merge with a creature they kill, which creates low hybrids, this process does not always work, the power of the created hybrid depends both on growth stage of the shadow and the power of the creature that was killed if shadow devours a arcanist it will sometimes make a banshee, and extremely fast, powerful and hard to kill hybrid. The high hybrids in contrary are a direct result of the cataclysm.
Shadows are not conscious or intelligent, but they have this collective cunning, they stalk their pray and wait for it to be weakened or distracted, sometimes for many days. Shadows are quite skilled in stealth, it takes an experienced tracker to spot a stalking shadow. Shadows can and will hide while in natural shadow, they become functionally invisible.
All shadows can understand Darkspeech and some can speak it. They often cooperate with hybrids and listen to orders of some high hybrids (like Shadowfolk), they are never aggressive towards hybrids.
After more powerful shadows are destroyed a gelatinous substance known as Strands can be recovered, they are useful in alchemy, especially in creating some of the most insidious poisons, the possession of this substance is highly illegal.

Basic Information

Anatomy

All shadows are amorphous while melding with natural shadows. Shadowspawn and small shadows are generally amorphous Medium and large shadows can take various shapes, sometimes of beasts or humanoid but it is apparent that they are shadows. Greater shadows take shape of various beasts and monsters, they are bony with muscle-like black strands, the form is semi solid with weaponry melded into their form. Shadow Agglomerate show up only during the incursion, these are conjoined from thousands of shadowspawn and extremely dangerous.

Genetics and Reproduction

Shadows multiply in dark areas rich with arcane aura, they also tend to multiply better far away from civilization, the reason for that is unknown.

Growth Rate & Stages

While spending time in high aura locations smaller shadows can merge or grow into larger ones. The process of growth from shadowspawn to a greater shadow would take several centuries.
The stages of growth are: shadowspawn, small shadows, medium shadows, adult shadows (most stay at this stage), greater shadows

Ecology and Habitats

Shadows prefer to live in dark areas with plenty of natural shadows, they hide from light during the day (unless there is a powerful arcane aura), they prefer ancient ruins, caves, the Crater and Shattered lands, some also live deep in severs underneath large cities. Most stay away from civilization. During the night they creep forward the towns and villages, that is reason why most of these places are protected by Eliseri Lamps.
Shadows can be find in every land, on every continent, some also live under water in great oceans and seas of Era.

Dietary Needs and Habits

Shadows sustain themselves on arcane aura, if available they will devour arcanists and also most living beings.

Biological Cycle

Shadows are effectively immortal, or rather not alive at all.

Additional Information

Perception and Sensory Capabilities

Shadows have no sight and rely on sensing the arcane energies and blindsight. Shadows also sense when something creates a moving natural shadow (like creatures in light), the range of this ability is uncertain but larger than blindsight, they can also sense a presence of light. The larger and more powerful the shadow is, the more honed their senses are.
Shadows have innate ability to detect arcane magic and arcane magic users, they attempt to hunt and devour arcanists. They hunt high elves with exteme prejudice, they can sense a high elf anywhere in the world, and one showing up on material plane would be dead within minutes.

Civilization and Culture

History

There are no historical records of shadows from times before the Reckoning.
The shadows were created by an unknown deity as a punishment for Eldacar Solar Aegnor Amasiader and the entire High Elf species for their usage of forbidden arcana and the betrayal of that deity.
Shadows were first seen in Era during the Reckoning and the first Long Night, any living creature close to epicenter of that catastrophe were either turned into a hybrid or killed by shadows, in lands of current Valar Empire most living creatures were killed. They also were the force that killed every high elf that did not escape to a different plane of existence. Wood elves and sea elves were spared, but only ones far away from the Crater, most Drow were spared.
During the first Long Night shadows were the crucial danger to survival of civilized species, many techniques to fight them were devised back then, some used to this time.
During the Era of Twilight (time just after the first Long Night, lasted for about a century) most shadows and hybrids became more docile and most retreated into the Crater, Shattered Lands and any dark, cozy place. They were still a significant danger and hindrance for spread and growth of civilization, the eventual discovery of Kadmin and its spread around the world in second century AR and later the invention of Eliseri Lamps in 352 AR, made Shadows into much more manageable threat.
Currently Shadows are mostly dangerous to travelers, explorers, ruin divers as almost all settlements have some sort of protection. They still can become a vital threat during the incursions.

Gameplay Considerations:

AC: 10 for Shadowspawn, up to 22 for Greater Shadows, counts as natural armor
Speed: 20-50ft
Damage Immunity: psychic, poison
Damage Resistances: magical damage, either from magical weapons or arcane magic
Damage Vulnerabilities: kadmin alloy weapons, radiant damage from divine magic
Condition Immunities: blinded, charmed, deafened, grappled, paralyzed, petrified, poisoned, prone, restrained, unconscious
Skills: Stealth

Shadows are disadvantaged by bright light, and will be damaged by sunlight or a presence of divine source of bright light
Shadowspawn deal psychic damage
Lesser, medium and adult shadows deal bludgeoning and psychic damage
Greater shadows can deal slashing and piercing damage and also psychic

Adult and Greater Shadows have and aura that hurts living beings and distracts them (cause disadvantage on attacks and ability rolls)
All shadows can dim light sources as an action (except lanterns which also hurt them), if made by spell they have to succeed at the wisdom test (wis + prof) against DC of 10+ spell level (advantage against arcane spells)
In darkness and dim light shadow can become invisible as a bonus action, this lasts until the beginning of their next turn. They cannot attack while invisible.
Adult and Greater shadows can use spell like effects up to few times per day, this include Dispel Magic, Darkness and others.

Conservation Status

In every culture of Era shadows are either avoided or killed on sight. Shadows are a vital and existential danger to all of the living. Possible destruction of Shadows is one of the most significant direction of research and study in Valar Empire.