Il'sariadh, meaning "Echoes of truth," is a craftworld primarily known for its scholars and artisans. It was almost a generation after the Fall before they were visited by Phoenix Lords and adopted their teachings, incorporating them into their own attempts to survive the influence of the She Who Thirsts.
Their late arrival might be one of the reasons why Il'sariadhians' views about nature of the Paths often put them at odds with more puritan craftworlds, as they claim that in order to learn the truth of the universe, it is necessary to remain aware of their prior Paths in a much greater scope than others.
Whether by employing such a stance they put their souls at greater risk to the Great Enemy remains to be seen, but short term effects are evident in the craftworld's culture.
Il'sariadhian art is known to be fairly syncretic, their craft often incorporating and merging elements which would have required a collaboration of multiple artists on different craftworlds. Their martial doctrine also reflects this approach, with the caste of elite warriors, called Menshad Korum (plur. Menshad Korii), whose form of exarchy manifests in pursuit of multiple aspects of the Bloody-handed God.
Corsairs fed up with violence often find life on this craftworld pleasant, and relatively small part of its youths leave it permanently to become outcasts or exodites.
However, those gains are not without price. As Alaitocii often point out, in their approach, Il'sariadhians balance at the edge of the knife, a small lapse in control away from falling to excesses that brought the Fall. It is from this craftworld the most vicious corsairs are said to originate, and many who stray from their Paths are drawn to the depravities of Commorragh in further search for themselves; some adapt to the cutthroat life in the Dark City, but most quickly meet true death in the hands of the Dark Kin. Still, a handful who return having freed themselves from the Path of Damnation bring valuable experiences, having taken steps of the founding ancestors, turning away from the short-sighted pursuit of uncontrolled sensations.
Il'sariadhians are sometimes seen as annoying meddlers. Contrary to most craftworlds, Il'sariadh doesn't claim responsibility for any exodite world, nor does it claim a swathe of space as their territory.
Its Seer Council grants a great degree of autonomy to their agents. It is not uncommon for the craftworld's seers and autarchs to operate in remote corners of the galaxy for decades, utilizing Void Stalkers as their mobile bases, pursuing their goals on various worlds nominally belonging to other craftworlds' influence zones.
From an outside perspective, their actions would often seem contradictory; from peaceful traders and mon-keigh lovers, to vicious warriors willing to fight alongside Commorites. More recently, some would also whisper rumors about Il'sariadhians performing research breaking millenia long taboos…
Except for a few hereditary Noble Houses, Il'sariadhians eschew a concept of surname and lineage; it is not the birth that should define an Aeldari, but his deeds. Most of the craftworld's nobles function more akin to associations of like minded eldars; runes signifying houses added to their names as either declaration of support or a sign of recognition rather than ties of blood.
The craftworld is guided by its High Council of the Seers, the body itself led by the Head Farseer. However, despite their influence, to enact their plans, the seers require support of the Asuryani willing to follow them, be it in the form of backing received from the Noble Houses, autarchs, or exarchs willing to follow their predictions. While most of the regular troops are easily available to further their visions, some of the more specialized ones have closer ties to certain families.
Mayor factions
House Il'sari - the original house of the craftworld's creators. While it owes much of its influence due to their historical significance, to this day the goals of this family appeal to the numerous seers. Their position as the craftworld's founders allowed them to create a tight relationship with certain Aspect Shrines; by making sure that only their members trained within them, even the Exarchs hailing from them remain loyal to their causes (mostly Warp Spiders Shrines, which proto-versions has been formed even before Asurmen's arrival on Il'sariadh).
House Invash - House Invash was one of the first houses to join Il'sari's efforts to construct the craftworld many arcs before the Fall. From the very beginning they maintained their position as Fir Caurifel, a titan clan. Matriarchal, their female scions carry Isha's blessing, often giving birth to twins or triplets, an occurrence rare amongst Aeldari, especially nowadays. However, the blessing became also a curse after the Fall; their male offspring are said to be always infertile, as do most female twins.
House Eldren - a relatively young house that took its current shape only within the last millennium. A gathering of merchants, known for their relative open-mindedness towards xenos, which often put them at odds with more traditional Asuryani. They believe that alliances with xenos can't be avoided given the current state of Aeldari race and push for long-term beneficial cooperation rather than one-sided exploitation of an ally of convenience.
House Karesh - the core family of House Karesh could trace their lineage back to the millennials before the Fall. Those tying themselves with them value tradition and believe in Aeldari supremacy. Numerous Il'sariadhians view them as decadent. They are rumored to maintain ties with the Dark City, some of their members going as far as to participate in Commorities' raids for the thrill of xeno hunting. It is said that within their territory, there are still Aspect Shrines that remain true to the teachings of the First Striking Scorpions Phoenix Lord.
House Praie - a mercantilish clan of corsairs that originally allied themselves with Il'sariadh in the turbulent years shortly after the Fall. Being the most competent void combatants the Craftworld had, the clan quickly rose to prominence, shaping its emerging naval doctrine. Praie's influence is one of the main reasons for Il'sariadh's reliance on the patterns of vessels traditionally associated with corsairs fleets.
Those Asuryani drawn to adventure, who lack excessive compassion for xenos would easily find themselves at home amongst them. Most Il'sariadhians (those not associated with House Eldren) don't necessarily consider them malevolent, but mercurial; restless eldars seeking the thrill of battle, testing their mettle against worthy opponents. It is said their pride is matched only by that of members of House Karesh (who often view Praie as nothing more than a gathering of vagabonds).
Despite their misgivings, no Il'sariadhian can deny that those allowed to add the original Praie rune to their names are unmatched void-combatants.
Minor factions
House Thuyelsa (sometimes transcribed as Thuyela) - when the craftworld Thuyelsa was destroyed, its survivors found refuge on Il'sariadh, and named themselves as such, to never forget their origins. Once known mainly as impeccable crystal artisans, their descendants still develop the craft, although their designs are seldom solely aesthetic now. Thuyelsan crystals are highly valued by bonesingers creating Fire Prisms, said to be unrivaled when utilized in energy weapons. Those not blessed by Vaul, often take Khaine's Path, becoming unparalleled warriors. Like most contemporary Houses, nowadays it's not the ties of blood, but the core idea which unites the clan - any Asuryani pursuing revenge on mon-keigh or mastery in martial aspects of crystal sculpting is welcomed in their ranks.
House Naer - an old, close association of like minded scholars and seergineers. Naer is a surname/title assumed by the faction's leaders. Influential, especially in recent passes with the ascendance of Arhorwal Naer to the position of the Head Farseer. They oversee production of vortex weaponry, and are rumored to conduct further research into warp technology.
Starleaf Union - a loose association of numerous bonesingers and artisans. Originally, the union formed as a means for its members to extract more pressure in the matters of the craftworld's politics. Recently however, with their growing opposition to Houses Praie and Karesh, some began to view them as an extension of House Eldren.