I don't have much background on my kabal since it's just exists in the backstory of my homebrew space marine chapter.
The kabal I haven't made a name for yet is led by a female scourge who also doesn't have a name. She had her wings torn off by my craftworld's head autarch when he had his forces turn on the dark eldar during a joint engagment. She managed to make her way back to the undercity. After making her way to be the head of a hellion gang, she horded enough riches to get a new pair of wings and then killed her ex-gang. She found one of the kabals that had been turned on by the craftworld eldar and involved herself with its archon personally, a rather lazy and self indulgent pudge. Once she had some influence over him she convinced him to reveal the craftworld's location to the homebrew space marine chapter, who took revenge on the eldar by slaughtering its population and burning it. During the campaign she killed the archon and took over the kabal, exacting her personal revenge on the head autarch by getting the chapter master to kill him and the entire farseer council while she kidnapped his daughter with the help of a baron of the Knight House that's connected to the chapter. With her revenge sated and now leading the kabal that's where I left off the writing.
Except for the part where she kidnapped the knight from before, titan and all, to fight in the arenas for a couple years. She messes about with the knight house from time from time, but isn't willing to incur the wrath of a chapter that burned a craftworld and its population. Actually I like the thought of her keeping slight relations with the house, just in case she needs a backup force she can manipulate.
if I do make that Ynnari army I'll actually do some models from the kabal.