To make up for the missing turn, and foreshadowing the next:
The Doom of the Amber Tritons
Once there was in the oceans of the Shadowshore a great and noble kingdom of tritons. This kingdom had risen in one of the millennia in which R'lyeh lay dreaming, when the polypal mothers stood barren and the aboleths, all save one, had buried themselves in the pelagic ooze to sleep.
The tritons were wise enough to avoid the deep places, and flourished. They learned the secrets of amber forging, and fashioned mighty arms and armor from it.
Then Auluudh crept up the continental shelf, out of the lightless deep into the blue and green shallows. Auluudh the Eldest, the Unsleeping Mind Lord.
And the Margrave of the Abyssal Edge in his castle of Kelp put on his finest hauberk of amber and swum up with his retainers to challenge the monster. But as the Margrave came upon Auluudh, a drowsiness came upon him, and his retainers, and they went back to his castle to sleep.
In the old triton kingdom, the tritons ruled, and the atlanteans were their servants, whom they sent up the shore to gather things and to trade with men.
They were kind masters for the most part, but the lightest servitude will chafe, while the most crushing slavery deadens all feeling. This the aboleths know, and this Auluudh knew.
So Auluudh conspired with certain atlanteans, and with the power of his ancient mind enslaved certain others, atlanteans and triton both.
And so it came to pass that when the king grew old, of his two heirs the elder grew haughty and the younger grew envious, for their tutors were enmeshed in the aboleths fetters. It is not known if the elder grew impatient as well or if the king did die a natural death, but for a surety his younger son claimed otherwise.
Each had their followers, loyal and passionate most, and some of them also old Auluudh's slaves. Words had been said that could not be unsaid, and now deeds were carried out that could not be undone. War came to the great and noble kingdom of amber, tridents flashed green and gold and blood billowed brown and the sharks glutted themselves on the dead.
Yet the brothers did not fight each other in the end.
The civil war's carnage had created in both a revulsion for bloodshed, yet the bitterness of fallen friends and the acrimony of their quarrel precluded a true peace. So it came to pass that the kingdom split into two halves, of which the elder and his followers retreated south into the Moon Sea, while the younger and his people struck out east, to make a new home in the Sea Untamed.
Of Auluudh nothing had been heard since before the outbreak of war, save perhaps that on the kingdoms north western edge the shark attacks were particularly bad, and the Margrave of the Abyssal Edge and all of his blood disappeared without a trace, while his castle of kelp fell to ruin and neglect.
More than a hundred years would pass until the stars would align, and in deep R'lyeh the Mothers would bloom and spew forth spawn in the dark, and the aboleths would stir and twist out of the sludge, and the Mind Lords would swarm out to capture fresh slaves.
And an ancient power would boil out of its lair, and the younger's kingdom would fall to its arms, while a mad prophet-slave would dance through the ruins.
And an army would assemble in the wakening city, and Auluudh would creep forth and crawl at its head, and the army would crawl out of the deep, and past the old ruin and towards the Moon Sea.