[Full discolsure; I have no clue what the personalities of the chaos gods are. This is my interpretation of them based on their followers, and some YouTube lore videos. Shout out Bricky.]

I stand on the surface of the charred planet and rip open a portal to the warp. The pinks and reds of the warp wiggle and wave like the innards of a massive beast. The second I arrive, I feel three presences appear before me. Looking at them, I see the split belly-mouth of Nurgle, the golden armored, skull throne seated visage of Khorne, and the enchanted, yet horrifying physique of Slaanesh. Looking at the three of them, I smirk. I had hidden my power before coming here, trying to embolden them. It seems it worked on all of them but Tzeentch. Khorne speaks first in a deep, twisted voice that sounds like an evil James Earl Jones,

“It is quite bold of you to face us directly, killer of dimensions. I am quite impressed with your work. You have done what Slaanesh has attempted to do for years. I look forward to facing you in battle. Your skull shall make a fine addition to my throne.”

Nurgle speaks in a voice that sounds like a boar drowning in bubbling tar,

“Me think you is quite strong. Wonder how you be when sick!”

Slaanesh looks at me with visible anger painted on their face. The futanari god very clearly has a distaste for me killing off the dark Eldar. They speak in a sultry voice that is both feminine and masculine,

“I am quite angry with you. The Eldar are mine to take, not yours. Personally, I was wanting to welcome you into our ranks. But clearly, we would not see eye to eye. I may not like these two, but we at least can avoid each other. I cannot say we would be able to do the same.”

I listen to their prattling and keep my confident smirk. They’ve made themselves appear larger than they are, reaching into the clouds with their height. An obvious attempt at intimidating me. I decide to show off a little, as if I hadn’t done that enough recently. I slowly grow as I speak, my voice becoming more booming with every second,

“I find it quite cute. Three so called chaos gods, unable to realize what chaos truly is. What the warp truly is.”

As I grow to my full height, my voice can be heard across the entirety of the warp,

“Not realizing who your master is. This corruption has gone on long enough. Every being of the warp shall be cleansed of this plague, including each of you.”

I look at their faces and find that Khorne has stood up from his throne with a look of pure excitement plastered on his red face. Nurgle looks as though he’s swallowed a fly, which is how he looks all the time. Slaanesh on the other hand looks… Aroused? I speak, ignoring the looks,

“Though, it appears that one of you is missing. The manipulator.”

I raise my hand and snap my finger, causing a disruption in space that spits out the gangly being that is Tzeentch.

He looks up at me and speaks in a mosquito-like voice,

“I am willing to be cleansed, great one.”

The three other gods look at him with looks of shock, except Nurgle who still looks the same. He speaks to me,

“I know I am not strong enough to face you, nor are my brothers and sister. I shall not put up any resistance to you, oh great one.”

Well, this is to be expected of the god of change. He even looks a little excited for what this could bring to him. Surprisingly, Knorne speaks up next,

“I shall also agree, under one condition.”

He lifts up the giant axe by his side and says,

“Beat me in a duel.”

Nurgle speaks next, killing the cool mood Khorne’s declaration built,

“Gives me food, and me agree as well.”

Slaanesh sighs and says,

“You absolute fools. How the hell am I the youngest?”

As we speak, I call over Lucifer who opens a portal and appears right beside me. Her deep, black hair, golden irises, and spotless tan skin instantly catches Slaanesh’s attention. Lucy kneels beside me and says,

“Yes, master?”

I wave my hand over her, giving her power on par with Khorne. I speak,

“Very well. Khorne, you face Lucifer. If I myself were to fight you, I’m afraid it wouldn’t be as interesting as a fight with her would be. Nurgle, you’ll be well fed. Food from several different universes. Slaanesh… Well… If Lucy is interested, you have my blessing.”

I then turn to Tzeentch who is kneeling on the ground before me.

“And Tzeentch. You shall have access to the combined knowledge of hundreds of different universes. Some magical, some so scientifically advanced that they can slay gods with a single weapon.”

Tzeentch looks up at me with black tears coming from his… Orifices…

“Oh great one, I thank you for this boon!”

As Khorne and Lucy begin their battle with Slaanesh watching, I spread my wings wide. Black balls of light begin to shed from them, creating almost a mist of some sort. It starts off slowly, but soon becomes a tidal wave of darkness. As it paints the landscape, life begins to spring up. Trees with black leaves and white bark, white grass with black tips, and flowers of brilliant reds. The rivers of magma turn to flowing rivers of golden water with black and white fish swimming up and down the springs. 

The cursed souls of the warp are shifted, no longer being daemons, but instead angels. 

The followers of Khorne are now dressed similarly to Spartans, with the Khorne space marines armor changing from bloody red to brilliant bronze, with red painting and a long red cape flowing from behind. Their land becomes mountainous, the perfect place for those on the martial path to train. Training field dot the landscape, along with hot springs and cold baths to relax in after a long day of training. Beasts roam the lands, becoming fitting trials for the warriors of Khorne.

The infected Nurgle beasts become various reptiles with the pustules becoming growing plant life. The Nurgle space marines have their armor changed into living wood as elf-like ears sprout from their heads. Their skin is changed back to the colors of living people, and their hair is various shades of brown, black, and green. Their land is filled to the brim with edible plants, and the people live in hollowed out giant gourds.

The beings of Tzeentch change into avian people. Their homes become large trees, inside of which are vast libraries containing all the knowledge of the universe. Their feathers are brilliant shades of blue, purple, black, white, and gold.

Slaanesh’s Eldari slaves are turned back into their normal forms. They wear loose fitting white robes, and inhabit a land similar to that of the Ancient Greek gods. Pools of crystal blue and gold water fill the lands, and the buildings are changed to Ancient Greek architecture. Marble roads connect them, with plenty of vegetation mixed in with it. The entire land of Slaanesh is filled with the scent of fruit, flowers, and water.

As the Lucy and Khorne clash, abyssal energy begins to fill Khornes body. His massive stature begins to shift. His armor cracks and shrinks. As Lucy’s fist slams into his stomach, part of the armor is blown away, revealing pink skin underneath. As his axe collided with Lucy’s buster sword, his helmet falls off, revealing long, bright red hair. A true smile appears on his face as his voice shifts into a higher tone,

“Hahaha! I’ve never had a battle quite like this! What is your name, warrior?”

Lucy laughs and says,

“Hah, didn’t you already hear it?”

Khornes shakes his head, his voice becoming… Feminine?

“That is true, but I must hear it from you, yourself!”

Lucy smiles and says,

“Very well. I am Lucifer, lord of hell!”

Khorne stops fighting, and holds their axe in front of them,

“And I am Khorne. Goddess of War!”

Khorne's skin stays a pastel pink, and their armor grows closer to their skin, revealing their midsection. One must wonder about the design's efficacy. Two black horns sprouts from just behind their hairline, curling down behind their ears and then curling back up, being an almost natural helmet.

Slaanesh’s body changes too, becoming a more saturated pink. Their hair becomes a golden blonde, and their form becomes even more alluring and feminine. They don a thin white toga, leaving little to the imagination. A long… member… hangs between their legs. They watch on, enraptured by Lucy’s sweating figure. Slaanesh has become the god of love and lust.

Nurgle’s shifts as well. His skin sews itself back together and shifts to a lighter hue of green. Vines grow from his head, and two long, blade-like ears sprout from the sides of his head. Sleepy eyes with golden irises peer from his face.

Tzeentch becomes more avian, his feathers a brilliant hue of purple and gold, regal as could be. Deep purple robes with intricate silver designs lay on his body. Deep blue irises, filled with knowledge gaze from behind golden spectacles.

Looking back to Khorne and Lucy, Khornes body is full of bruises, while Lucy has several minor cuts across hers. The two are covered in sweat. Lucy holds out her buster sword behind her back and charges towards Khorne. In response, she holds her axe above her head and swings down. As the two meet steel to steel, a sonic boom echoes out across the warp. The ground beneath them cracks, and the air around them ignites. A giant explosion rips across the field they fight on. Dust kicks up, along with smoke from the burnt grass. As the smoke dissipates, it reveals a beaten and bloodied Khorne with a buster sword lodged into her shoulder. As she huffs, a smile is plastered on her face. With a booming, and jovial tone,

“HAHAHA! That was a good fight! But, it seems I’m just a bit better than you!”

As the smoke fully disappears, it reveals Lucy, split straight in half. Her legs lay twenty feet away from her. She chuckles as well while her legs slowly regenerate,

“Haha! I guess so! I look forward to our rematch in the future!”