(General POV)
Location the Nethervoid, just outside Castle Oblivion
Laharl decided to walk out his castle instead of simply teleporting, as he though he must be the only one amongst the Chaos Gods that actually moves around from their personal dwelling in their domain with exception of war between them which in his mind is both stupid in lore wise basically is was a way to make lazier lore from GW without having the Chaos Gods do actually physical action and also means it be easier to find them once they each are born.
Despite Laharl precautions for the upcoming wars between himself and the other Chaos Gods he is also eager to face them, beat them, and dominate them because he'll change the Eternal Game completely to his favor.
Laharl spreading his enhanced black feather wing, whiles doing this the three clawed black fingers on the edge of his wing also stretched he closed his eyes sensing across the Nethervoid for Ba'al and after a few moment he located him, still but moving it was strange experience but he didn't care as Laharl flapped his wing hard lunging himself into the maroon skies of the Nethervoid feeling the new strength of his wing heading the south of his realm noticing his speed has greatly increased as well making the Chaos God of Carnage grin as he increased his speed more blasting through the skies towards the location that Ba'al Allseer is.
Location the Nethervoid edge, a Floating Isle the Abyssal Library
As Laharl flew through the entire Nethervoid in speeds that he was only able to achieve at his full use of his power and speed but now he using the same level of speed and he can tell that he was barely using all his strength to achieve this kind of speed, exciting the Chaos God, as this meant that only physically but also all his other capabilities and powers has grown as well.
Laharl arrived at the edge of his realm as the warp of surging colors and chaotic energies was just before him as he stopped floating in place with the occasional flap of his wing, when he sensed Ba'al power closing in the area turning his sight towards the direction and saw a colossal piece of earth floating over the edge of his domain that explained the strange experience he felt while sensing the Great Seer, bursting toward the cloister of earth ascending to it top.
In a few seconds Laharl passed the height of the cloister once again stopping himself floating in place as he looked at what is the domain of the Great Seer he saw the violet ground of the Nethervoid with thorn covered, marooned colored vines stretch, coil, and spread across this cloister, but the largest amount of this thorn vines were in their own cluster in a massive dome of thorns and maroon vines this is where Ba'al essence and power was emanating from, as Laharl landed on the ground he was greeted by several Void Wraiths that bowed their hooded phantom form before him as one that the Dark One commanded to speak and tell him of the new domain of Ba'al it confirmed and started telling him what the Great Seer has done...
The Void Wraith told Laharl that after he dismissed Ba'al commanding him to form his own territory and scribe through the timeline he flew across the Nethervoid taking a small piece from one of the mountain spread across the hellish domain of the Chaos God of Carnage, using the power granted to him by Laharl to manipulate the warp through this "small" piece of the Nethervoid expanding it to it current size those dark powers affected the daemonic roots that once were benighted the violet earth resulting the vines that protect the Abyssal Library, when the Void Wraith said that the Chaos God commanded him to explain what is the Abyssal Library.
The same Void Wraith bowed as to confirm his command to better explain the Abyssal Library and continued speaking in it ghostly voice that the Abyssal Library was created by Ba'al to serve as his private dwelling, and were countless Void Wraiths have taken residence in desiring to learn and master more secret of daemonic sorcery but after all was done what was supposed to be a fortress at first became what is now as within the deepest part of the Library the Great Seer went into a trace as he enter in the strands of the "Web of Time" as they refer the timeline and branches, and since he ordered him to do so and search for useful and beneficial events, and world for him so the Void Wraiths that came to the Abyssal Library started writing down Ba'al visions regardless if the outcome is beneficial or ruinous for him and the legion of carnage.
This reminded him a lot of Kairos Fateweaver lore but the difference is his son and the first general of his daemonic legions impressing the Chaos God as Laharl thanked the Void Wraith for inform him that he decided to ascend this very Void Wraith into another Spectral Herald rising his herald to two in the amount under his command pleasing Laharl as the six-armed horned herald wielding his Chaosbrand Staff, bowed to him as they all started to make way towards to the thorn covered Abyssal Library to see it for his own.
Location the Abyssal Library
As the thorn let Laharl passed into the cluster as the Abyssal Library stood before him floating in the air not touching the violet earth, Laharl saw the triangular spikes on the lower part underneath the structure as raw warp and daemonic energy thundered and surges through them and crashing against the daemonic earth as those energies were mutating the ground as abominations that should be on a Chaos Spawn sprouted and move from limbs with claws, pincers or tentacles, eyes, faces, and mouth covered the area the library covers in shadow and flow chaotic energy to this landmass, impressing Laharl as he then turned his view to other areas of the dwelling of Ba'al Allseer.
The colossal gothic/symmetrical structure of the Library is colored black, dark purples, and maroons, the entire structure with several spiraling spires, and towers all over the each with curved or triangular spikes of dark purple and below these spires and towers had several needles sticking out them with a spiraling black staircases over these towers, and spires leading to various doors up and down the towers, plus the main violet massive wide staircase spiraling to main entrance of the Library barring the mark of the Great Seer based after the "Mark of Carnage" looking up he saw the main building's roof was a living daemon head representing his mark except with thirteen eyes and a longer tongue swaying around, said head was connected to a violet cross this reminded him a eldritch library in all reality and the Chaos God, loved it he was impressed with Ba'al creation Laharl wrapping his wing around himself making like a makeshift feathered coat as the new claw gripped on his opposite shoulder pauldron as he walked towards the Abyssal Library to find the Great Seer himself and start discussing the next Chaos invasion of the Materium but also see what time they're on in the lore.
(Ba'al POV)
Location the depths of the Abyssal Library
As my father and creator, the Dark One, Laharl commanded me I have created my domain in the Nethervoid at first it was to serve as my private fortress as daemons ranging from Knightmares to Void Wraiths roam my library as many level in this pocket realm within, the realm of Carnage was created with the bending of the warp itself using my own power and feed by the Warp to control this maze of despair.
Levels upon levels of chambers, staircases, shelfs, either connected or floating aimlessly within the Library as these Void Wraiths craved my knowledge on dark sorcery many have agreed to serve under my command in the legion of carnage, once I created my home how I wanted, I reclused myself in the deepest chamber/level of the entire library to scribe through the Web of Time as my master commanded as I search for world useful to us, I've already discover three the world of great ice and shadow Ymir a recent conquered world at the edge of the Eldar Empire, the rock and rough plains and canyons of the world Thraakhi with warring Greenskins worth conquest and the harvest of souls, and a world which is Kolbaline that possess great psychic defenses that prevent me from entering it in my scribing but I see great Chaos as a war unlike all is waged upon it mortals and the daemons of Chaos...glorious...all the while my mouth prophesize my visions these servants of my write tomes and books of my journey through the Web in only nineteen days much of the first section of my library was filled with the possible branches that will or may not occur on Kolbaline but this world should be are first three great Queens shall rise from the ruins of said world...
As I exit my trace and my eye rolled back to normal I saw before me my Master, the Chaos God of Carnage, Laharl stand before me I greeted him and welcomed him to the Abyssal Library of the Warp...