The Null Ocean, Far Realms

The laws of reality are broken in the far realm, leading to mere concepts taking physical shape.  
A vacuum liquified.

An emptiness solidified.


Non-existence given form.
  Any creature that falls into the Null Ocean is immediately infected with a magic disease called Void phage. Alternativly, there are parasites and the ooze that can inflict void phage.

Void phage:

Any creature that becomes grappled by the ooze must make a constitution saving throw or become infected with a magic disease called Void phage. It must repeat the saving throw at the start of the ooze's turn if it's still grappled.
While infected the creature can't take long rests and an amount of untyped damage equal to the target's Hit Die every 12 hours. Only a Greater Restoration spell can cure the disease.
If the target reaches 6 levels of insanity before the disease is cured, it transforms into a voidling. Only a wish spell can reverse the transformation.
Beast: Void Wolf Elemental: Humanoid: Void Marauder
Celestial: Voice of the Void Fey: Null Satyr Monstrosity: Void Drider
Construct: Void Golem Fiend: Void Armanite Ooze: Void Ooze
Dragon: Ancient Void Dragon
Adult Void Dragon
Young Void Dragon
Giant: Undead:

Blight Flame

A fire born of death and decay.

Frostspark

Lightning that lost all heat, gaining the biting cold of the deep.
Type
Void