No one knows where they came from, there are only vague stories, rumors, legends. The concept of four dooms can be found in numerous stories across the galaxy, even on Earth there are tales of The Four Horsemen of the Apocalypse. All that is known is when the four come together, horrific things happen.
The Four Tempests possess various powers. They are extremely durable, able to exist easily in harsh environments. They are at least several times stronger than a normal human being, with Taucass being immensely strong. They can sense one another over light years of distance and can communicate telepathically.
Veshuthru, Lord of Marrow
A powerful sorcerer, Veshuthru possesses a wide range of abilities centering around the manipulation of matter, especially organic. Veshuthru has been seen tearing the bones right out of a person, or fusing multiple bodies together to create horrific monstrosities under his direct control. He is also able to manipulate tons of stone as well. Veshuthru likes to don an armor of "living bone" that is tremendously durable, he will also create a stone sword far stronger than whatever material her originally made it from. Allied with his "siblings" his powers grow in strength.
Hexamoquor, Queen of Blood
There was a period only a few years ago when the Tempests had forgotten what they were. It was speculated that an enemy of theirs had wiped their memories somehow. The being known as Hexamoquor actually found herself employed by the Confederacy Elite in the guise of Sableblade. When one of her siblings discovered her and restored her memories she went on a vicious killing spree, killing dozens of soldiers with malicious glee.
Hexamoquor is tremendously fast and possesses the fighting skills of a dozen cultures. When she slays a person she seems to feed upon their life force and temporarily grows stronger and more durable and is able to heal far more quickly than she normally does. Hexamoquor is also able to control a person she has wounded, turning them into her beserkers. Of the four Hexamoquor possesses the greatest military/tactical acumen.
Taucass, Monarch of Might
Sentient power, that is the best way to describe Taucass. He is a being who is able to employ his power into fantastic feats of strength, or release devastating bursts of energy. Taucass is the toughest of the four, the hardest to harm and the most difficult to keep down. Taucass is also the least intelligent, with a difficulty in understanding complex concepts. Alone he is actually calm and almost likable, a being who mostly only wants to be left alone. But among his siblings he becomes far more violent and prone to acts of destruction.
Taucass' form can change to some extent but he usually appears as a three meter tall humanoid with a belly full of roiling energy.
W'Shilm, Prince of Pain
While is appears that W'Shilm is comprised of some form of energy his body is very much corporeal. He is a master manipulator, one who can read and control the minds of any sentient, be it a primitive beast or the most advanced artificial intelligence. W'Shilm can influence emotions, twist memories, temporarily turn a good person into a depraved monster. In a way W'Shilm is the most dangerous of the four because if he so chooses he can attack from the shadows because unlike the others he is also able to change his shape and manipulate sensor devices to see him as he wishes to be seen.