1 History and Explanation/Information

History

Billions of years before the universe was created, There was only 'The Brilliant light' and 'The Absolute darkness', The Absolute Being divided The Brilliant light into The infinity stones and the celestials. And the Absolute Darkness into Demons and store a portion in Ashborn.

Ashborn was the general of the absolute being's army. After seeing the loyalty of Ashborn the absolute being hided the a portion of the absolute darkness inside him without his knowledge. Ashborn was the strongest being after 'The Absolute Being'.

The Absolute being was getting bored nothing entertained him anymore, so ordered The Celestials to fill the empty space and create ten realms.

The Absolute being was planning to send the six infinity stones and the Celestials and Demons into the Chaos realm and watch them war against them self.

When Ashborn figured out The Absolute Beings plan. He started a revolt against The Absolute Being. Ashborn was about to die in the battle against The Absolute Being, but the fragments of The Absolute darkness enveloped him and tuned him into The Shadow Monarch and rise his companions from the dead, when Ashborn came in the throne of The Absolute Being, The Absolute Being had was about to die by the other Celestials. And before his fake death the Absolute Being had Sealed Ashborn to a planet called Earth.

Explaination/Information

So Knull is actually one of the fragment of the absolute darkness which is not created by The Absolute being, and Knull is much weaker than Ashborn.

The Celestials are not like the Celestials in Marvel, they look more like 'Rulers' of Solo Leveling. And the Demons include creatures like

Mephisto, Dormammu, Blackheart, Zarathos, etc.

So the Powers of the Shadow Monarch includes:

Dimensional Teleportation.

Time Stop.

Reality manipulation.

Resurrect. (Can make the dead alive but the person's body should be in good condition, can make them his shadow soldiers or can make them undead.)

Shadow manipulation.

Creation of all things.

And some basic things like healing, regeneration, Psychokinesis, mind manipulation, illusions, super strength, super speed, ultra reflexs, etc.