Nocturne If I am Correct
In Lux's short story "For Demacia" we are shown a nightmarish being that serves as the main antagonist of the story. If I am correct on my assumption, this has been confirmed as Nocturne. Today I would like to go in depth and list all that Nocturne can do which might help to guide a future VGU for him. Link for the story can be found below.
What We Know:
Nightmares: Pretty obvious, also makes you taste rancid milk in your mouth. Odd. "Lux awoke with a scream, her heart hammering in her chest and her breath coming in wheezing spikes. Terror filled her mind; a nightmare of clawed hooks dragging her beneath the earth, of fetid mud filling her mouth and darkness smothering her light forever. Lux blinked away the last afterimages, glimpsing retreating shadows out of the corner of her eye."
Terror: Drives a good Demacian to murder his family and neighbors by making them appear as monsters. “No!” cried the man. “You don’t understand! They were monsters! I saw them, their real faces! Darkness. Only Darkness!” “He murdered his wife and children in their beds, then ran out onto the streets and attacked his neighbors. He split three people with an axe before they were able to restrain him.” “Not them. No. I saw. Weren’t them, they was... monsters...” sobbed the man. “Darkness clothed in skin. Among us the whole time! I woke and I saw their true faces! So I killed them! I had to do it. I had to!” "Lux dropped to one knee as myriad visions of horror arose within her; choking fears of being buried alive, of being driven from Demacia by her brother, of a thousand ways to die a slow and painful death. The light within her fought these terrible sights, and Lux’s breath shimmered with motes of light as she spat the taste of death from her mouth."
Making People Fall Asleep: Made Lux feel sleepy and put a whole town to sleep. "Then, one after another, the people of Fossbarrow fell to the ground, as if the life had simply fled their bodies." "Lux heard the soft susurration of grave cloth being pulled tight. Sleep… “No,” she said, gripping her staff, but the unnatural weariness slipped over her like a comfortable blanket, warm and enfolding. Lux’s head dropped and she closed her eyes for the briefest instant."
**Spectral Appearance: ** Pretty obvious and already known, just some fun imagery. "The magistrate recoiled in shock as a phantom form of wicked claws and searing eyes erupted from the dead man’s skull. The spectral darkness launched itself at the magistrate with a cackle of spite."
**Nightmare Creatures:**After putting them to sleep, Nocturne gave form and mass to the inhabitant's nightmares. Dies in one hit. "her mouth fell open as she saw black, vaporous shapes lift from the town’s unconscious inhabitants. No two were alike, and Lux saw an assembling host of demons in Noxian armor, vast spiders, many-headed serpents, towering demon-warriors with frost axes, great drakes with teeth like obsidian daggers and scores of things that defied sane description." "The shadow creatures closed on the platform, sliding through the air without a sound. An oncoming tide of nightmarish horrors." "Oil black demon-hounds were the first to reach the platform, leaping upward with tearing fangs and flashing teeth. Garen and the Dauntless Vanguard met them with shields locked and blades bared. A hammering wall of iron beat them back. Though their enemies were wrought from shadow and spite, they fought with ferocious strength and skill. Garen stepped in and thrust his blade into a writhing beast’s haunches, tearing through to where its spine ought to be. The monster’s form exploded into black dust with a shriek of anguish."
Landscape Changes: Simply put he makes everywhere look evil and crap. "The closer she came to the tomb, the more the landscape began to change, taking on an altogether different character – like something from a tale told to frighten small children. The trees wept a sickly black sap, their branches gnarled and twisted into clawed hands that plucked at her hair and cloak. Gaps in the boles of trees resembled fanged mouths, and venomous spiders spun cloying webs in their high branches. The ground underfoot became spongy and damp with brackish pools of stagnant water – like a grove abandoned by one of the fae folk."
**Possession:**In the story, Nocturne possesses a young boy with magical capabilities. "A young boy, no more than twelve or thirteen sat cross-legged before it, his thin body swaying as if in a trance. Tendrils of black smoke coiled from the tomb, wrapped around his neck like strangling vines." "He turned to face Lux, and she faltered at the sight of his soulless, black eyes. A cruel grin split his face." "His eyes rippled with darkness, nightmares waiting to be born from the rich loam of human frailty." "“I made him sleep, and his dreams were ripe with horrors to be made real,”" "Lux poured her light into Luca, and blinding radiance exploded through the clearing. The monster within the young boy was torn loose from his flesh with a howling screech of fury and desperation. White fire enfolded her, becoming everything around them. The darkness fled before Lux’s awesome power, its shadow banished by the incandescence of her light."
Additional Info: He killed Lux and Garen's Great Grandpa
TL;DR In summary, Nocturne is a nightmarish spectre capable of possession, inflicting nightmares, terror, and vision, raising an army of shadow beings that have substance, and putting a whole town to sleep. He can be exorcised by use of magic(see possession).
This information gives us a whole lot more to work with in terms of shaping Nocturne's identity both in lore and in gameplay. Also for those wanting a link to the story - http://universe.leagueoflegends.com/en_US/story/for-demacia/ There you go.