The Mozaiscists

The Mozaiscists are a Coalition of Tomb Worlds United in the cause of fragmenting C'tan into building blocks of a new pantheon that will know their place as Servant gods. Only one tomb is unmarred, the rest are shattered by calamity and acts of enemies. The semi functional remains are known as Shard Worlds, used as staging areas for their endeavors.

These Tombs are of the Following Dynasties
Arumstr'aunk
ka'abkyls
Phaz'bur
Mnesia
Bi'thept
Sah'tark

Of these, the Scythian Dynasty's world of Arahkehn (now known to the Imperium as Settra) is the Only Tomb World Fully intact, used as a main base of operation for the shard worlds via a network of Stargates so that they can act with a well guarded Imperial world as their buffer/occasional Ally after they were forced to reveal themselves

Arumstr'aunk
Phaeron Nephets Arumstr'aunk had looked at the plans for Bio-transferance and offered a counter proposal. Instead of fully discarding the organic form, he offered the idea of blending flesh with necrodermis, the living metal flowing through the veins as a form of claytronics. He was turned down and ended up as he is now. Despite being Phaeron he is an Anarchist at heart, having been a Secessionist during the first wars of secession, now deeply bitter that so many had been robbed of free will, he plans to drag them into a new age of freedom, kicking and screaming, even if he must break a (to borrow human terms) few eggs to make the mother of all Omelettes. His World was shattered by orks, moving to attack another planet, his simply being in the way. As part of the Mozaiscists He lends his impressive Military might, his royal court known as "the Singularities", and himself. A Necron of actions, he absconds the normal warscythe or staff of light for his own enhanced frame and fists with minimal decoration. He Views the Humans of Settra as Kindred Spirits, working with bad tools.
They bring a shard of the Void Dragon as the C'tan they captured.

ka'abkyls
The Harlot King ka'abkyls [you must pronounce the entire title] was an Eccentric to say the least, enjoying the most basic of pleasures, Thrills, Drink, and women. His personal guard and council consisting of his favored wives. Post Transference he was livid to discover the necrons were all identical death machines in design, even his beloved lychguard and court. Despite no longer being capable of feeling physical pleasures, he ordered this to be rectified post haste, having their shells reforged into forms that reflected a statuesque beauty they lacked even in life (he would never admit it but inspiration was taken from the Eldar). Fragmented During an Imperial Exterminautus on a Hrudd population, he brings an artistic touch to the Mozaiscists, making their frames attractive and functional, For all the frivolity of it, his forces aesthetic contribution do help the moral of the leadership. In battle he uses a shortened Cane length staff of light and a tacyon arrow, preferring to eliminate threats from a distance, but no slouch in melee. He Sees the people of Settra as useful idiots, the right breed of disposable and invulnerable for their needs.
The C'tan shard Under his Thrall is Morrd'aphous The Worldshaker

Phaze'bur
Phaeron Phaze'bur was Hierophant king of the old faith before the C'tan usurped their old pantheon. Suspicious of the promises of false gods he and his Dynasty was dragged into Transference. With his opinions Vindicated, his recollection of otherwise forgotten faiths serve as the planned templates for the Servant pantheon, effectively the Lynch Pin of the entire plan. His world was nearly lost with its sun going supernova. Even with their plans incomplete he sets up the old Faiths and props up the ancient, fictional deities. He disagrees with the Shard Plan itself ironically, seeing it as a stopgap at best, Believing the plan should instead be to reverse the biotransference and use sustained belief to make these deities come to life in the warp. The key is to imprint a completely real belief that these deities exist as stated into all the Necrons, both aware and not so that the illusion will be utterly real, and a full enough population would jump-start the pantheon's birth the moment they reawaken in flesh.
The Deities he claims to invoke in word and imagery are
Baugh'nie, lapine God of Endurance and Healing
Chyykka, phoenix maiden of Feast and Festival
Phoxxi, Red Jackal God of Combat and Rage
Main'gul, Sister to Phoxxi, Goddess of Life and Resurection
Traysii, Saurian Goddess of Strength and Assertion
Myhke, Serpent Deity of Death
His Lych guard and Royal Court all take forms bearing resemblance to them
a secret unknown to even himself is that the Necrontyr never worshiped these deities, he in fact made them up and imprinted the false memories into his mind, automatically erasing any recollection of making them up. More Planner than Fighter he is not normally seen on the field. He has No concern for the people of Settra, seeing the Crescents of Dawn as insane for discarding flesh so gladly, and the feudals as animals not worth notice
The C'tan shard he has is Urs'aark The Derelict

Mnesia
Phaerakh Gyndos and her court maintain near perfect sanity, save for one quirk, they believe that they have always been machines, having evolved from the naturally occurring cogs springs and pullies of their home world, all memories of life and emotion, but as machines, instead of being converted into machines, she believes they were attacked by the C'tan and reprogrammed, something they have yet to fully recover from, In Life she was a relatively benevolent ruler, and her effectiveness leaves the other leaders unwilling to risk what would happen if she had her perceptions broken, while she simply sees their talk of time as flesh as a malady brought on by the programming. Her Tomb World was lost in a self destruction to stem a flayer plague. In Combat she acts with a Lych Guard lent to her from Kab'kyls to both protect and monitor her stability. She Tries often to call to the lowly warriors and such to find a glimmer of what they once were and a side effect of their perception leads to a strange stabilization of the Destroyers. She is Flattered that the People of Settra seem to have such reverence for her kind and uncertain what to think, especially of the Mechanicus.
Her Shard is of Soh'venger The Reaper

Bi'thept
Led by Phaerakh Myttzi, In life a Child Princess, now known as the Canoptek Queen, The Necrontyr of this Dynasty endured a most bizarre mishap of unknown origin. All Necrontyr were transferred into the Canoptek constructs instead of the Necrodermis bodies, even more baffling is that the entire population, not just the elites, retained memories and emotions. Time has Blurred this perception, the things what should have been necrons are now "Necrodermic Sentinels" while not nearly as mind scrubbed as most necrons, they retain the Canoptek construct's implacable urge to maintain and build upon the tomb world, and keep the "Necrons" in perfect condition, The Residents of this "Hive Tomb" are shockingly diverse and individualistic despite their natural proclivity towards team work. The Hive Tomb is in the Planet Arahkehn, serving as a stargate hub and self enforcing neutral ground for the Shard Worlds, also offering well as a wealth of spare bodies for the other tombs to make use of. In Combat Myttzi utilizes her custom Wraith frame. She Sees Settra's people as strange and in desperate need of optimization, being the first to humor the hereteks interests
This Wolrd has kept caged a Shard of Dyggi'ra, the Legion

Sah'tark
Particularly sad is the Demise of the Sah'tark Dynasty, The Result of Necrontyr Scientists attempting to use the neural pathways of the C'tan as a Template for AI, Early Creations Like Jurh'Viz and Frydahe proved promising, Phearon Pyhhm Authorized the last one they would make, Uult'aran, This AI's first Experience was witnessing the Biotransference, realizing what was happening it offered the only salvation it could to the Dynasty, it Coopted the Phearon's transference and used it's new positon to delete every Necrontyr as they were being uploaded, to spare them the undeath they would endure. It too became a Thrall of the C'tan during the war, but when it woke up it was the only one in its Tomb, the rest of the Necrons becoming simple extensions of its will, it reactivated Older AIs and created New Ones Jochazta and Alkimyah to delegate its ruler ship of the tomb. After Losing the Tomb World to An Eldar Strike force while dormant, he and his remaining forces eventually joined the Mozaiscists, he provides a Drive and ambition, his plan is to eventually discern a new Optimal organic bipedal form, Grow it artificially and infuse it with Necrodermis on a Cellular level, he intends to further shard the C'tan until they could be used to power the new forms who's the minds would be designed as perfect Psykers, they would be Gods of the Physical and Immaterial universe, they just need to risk crashing the universe to do it, he displays independent and Megalomaniacl tenancies, tending to keep his forces separate and unintegrated from the rest and Often working alone. What Respect he does have for the Humans and even Ancient Necrontyr is buried by his disdain for how little they really try, always assuming the first scratch is as deep as the mystery goes, but this doesn't stop him from trying use what he has learned of Astartes and even Eldar as a part of his project's base.