M32 in the Imperial Timeline. For humanity it was just another eventful millennium but for the Noble Houses of Commorragh it was the beginning of the end.
To most Eldar and their darker kin, the 'Fall' is the creation of Slaanesh. For trueborn twins, brother and sister Cassian and Vincenza, the 'Fall' was when their House lost its influence, when they were forced to flee for their lives and when their ancestral home was destroyed.
For a while they managed to keep what remained of their power by staying mobile and taking up a Nomadic existence in the Webway. Unfortunately for them, due to having to constantly defend themselves against opportunistic raiding parties or repulsing assaults from newly formed Kabals, they were unable to fulfil their contractual obligations to the Haemonculi that supported them.
Without the safety of immortality the Warriors of their household defected, scattered to form their own raiding bands or even turned on the remaining loyalist supporters of Cassian and Vincenza.
Reduced to nothing, the twins came to realize that their house was truly dead; what was left under their command couldn't even qualify as a raiding party. So they decided to start again and they began by purging everyone left under their command because none could be trusted.
When that was done they adapted to the new ways and renamed themselves the Kabal of the Shattered Spire, a Duumvirate led by the twins.
In time Cassian and Vincenza found themselves a new home; a hollow asteroid in realspace in which they set up a portal connecting to an obscure, dilapidated and apparently useless network of webway tunnels. From this new home they ventured forth and scavenged, stole and murdered for what they needed. This allowed them to eventually set up cloning facilities in their asteroid.
Vincenza's initial instinct was to steal DNA from the most vicious and famous Kaballite Warriors of the time in order to grow the strongest possible army for their Kabal in order to strike back against the Black Heart and retake their ancestral home. Cassian wouldn't have it at all. Cassian argued that for their continued survival, not only should they avoid confrontation for as long as possible but that any force grown by them should be a trustworthy one and since the twins only trusted each other there was only one logical solution. Vincenza grudgingly agreed.
The Kabal of the Shattered Spire is tiny in comparison to virtually any other Kabal and whatever technology and vehicles they have, they've stolen from others or pieced together from salvaged wreckage. Nothing larger than a Raider can fit through the webway passages leading to their home and that's a double edged sword if there ever was one. Interestingly enough, the Twins treat their warriors with respect and the warriors are remarkably loyal to the Duumvirate Archons; the knowledge that they are one and the same creates a bond in the Kaballite hierarchical structure that simply doesn't occur in other Kabals.
Nowadays, ranging from their hidden base, Vincenza leads lightning strikes against vulnerable infrastructure or weakened raids returning from realspace and Cassian organises assassination and sabotage attempts. Their targets mainly belong to the Kabal of the Black Heart, which they delude themselves into thinking they're actually damaging with their actions.