I posted this on 40k Online a few years back when I was really into DE. I'm sort of getting back into the swing of things and thought I'd share it here. Pretty much your standard tale of betrayal and ambition, but it's believable.
Kabal: The Kabal of the Ivory Blade
Archon: Korrdeth Xyrnndien
History: Korrdeth Xyrnndien was but a dracon at the time Vect rose to power in Commorragh. A cunning Eldar, he served Archon Yyrileth Dargron of the Black Light Kabal. Dargron was an elder obsessed with his own stature, as well as his image – constantly launching raid after raid in order to preserve his youthful features. Whispers within the kabal remarked he was driving it into the ground. These raids were successful, no doubt, but with each attack the kabal lost warriors. The fighting force was growing weary and morale had dropped slightly. Dargron pretended not to notice his faults, being the self-obsessed Archon he was. Korrdeth was among those who despised his vanity, though he kept this secret from all but his most personal guard until the time was right.
This time would reveal itself as one of Dargron’s own slave raids. An attack upon the industrial moon Prometheus II was ordered, led by the twisted archon himself. Prior to the eve of battle, Korrdeth secretly met with the kabal’s warriors who sympathized with his distaste of Dargron. As the kabal mobilized for the raid, Korrdeth gathered his followers separately from Dargron’s main force. The archon’s warriors descended upon Prometheus II’s defenses, weaving through flak and autocannon fire. Though Dargron’s forces could outmaneuver the defensive fire easily enough, he was shocked to find barley half of his kabal had followed him into the battle. It was then Korrdeth’s warriors emerged from the webway at the flank of the archon. Ravager gunners aimed their dark lance turrets and unleashed fusillades at Dargron’s raiders, crippling the attack. Furious, Dargron turned his personal raider around and soared towards Korrdeth, anger burning in his obsidian-colored eyes.
Korrdeth saw the Archon heading for his craft and prepared to confront his dark master. As the two raiders neared each other, Korrdeth sprung from his station onto the deck of Dargron’s transport. Accompanied by a retinue of Incubi, he slaughtered the archon’s Trueborn guard and made for the raider’s throne. Before the elder tyrant could stand, Korrdeth was at his throat with his huskblade. The archon unleashed a string of curses and spat at the rebel dracon, but his words were cut short as the huskblade pierced through his abdomen and drained his pale body of vital fluids and lifeblood. Korrdeth threw the shriveled corpse from the raider, letting it fall to the defenses below. With the archon disposed of, Korrdeth and his followers disappeared from the raid, leaving the moon’s defenders baffled and weary.
Upon Korrdeth’s return to Commorragh, he took over the kabal as archon and renamed it the Kabal of the Ivory Blade, after his own sword which had put an end to Yyrileth Dargron.