Subjective Reality

Summary
Subjective Reality is a metaphysical ability that allows it's users to control what they define as fiction and reality. Specifically, this allows users to manipulate the borders between reality and unreality to turn one into the other or blurring the border between them. In short, users are capable of bringing anything into existence, including impossible things - especially impossible things, as fantasies care little about reality's limitations.

Variations
There are many different methods one can achieve Subjective Reality and many of these abilities often translates to completely different abilities or powers altogether
 * Reality Warping: Users are capable of altering how reality itself is through manipulating it's borders or simply making it unreal to begin with, making fiction or anything unreal the reality
 * Dream Meanipulation: One theoretically is capable of making whatever they dream into a reality or making reality itself the dream. This in a sense, allows the users to manipulate dreams themselves
 * Creation & Summoning: One could easily summon something from a fictional setting or create something that didn't exist in reality that did exist within a fictional media in-universe. This also extends to summoning entire beings who normally don't exist in reality and altering the border of reality to make them reality
 * Existence Erasure & Nonexistent Physiology: Through turning beings into fiction or simply unreality, one could erase another living creature from reality and make it to where they don't exist. This also extends to being able to make one's own self unreal and giving them nonexistent physiology in turn
 * Paint Manipulation: By drawing something that doesn't exist, like a drawing or a piece of art, one could use this to turn their paintings into reality and make them essentially reality
 * Power Nullification: By making a recent event unreal, the user is capable to undo and erase any consequence produced by it. The user could be capable to negate attacks, injuries and even death.

Weaknesses

 * Those who have Transduality are transcendental of both reality and unreality, making them completely immune to it's effects
 * Range could be a limiting factor to their ability and as such, someone who could get outside their range of effect would be less prone to their powers
 * Those who have Nonexistent Physiology (Absolute) could potentially be immune to this due to not being truly existent in any sense of the term

Users

 * Kumagawa Misogi and Ajimu Najimi (Medaka Box)
 * Maxwell (Scribblenauts)
 * Oryx, The Taken King and many users of Sword Logic (Destiny)
 * Yukari Yakumo (Touhou Project)
 * Madotsuki, Urotsuki and Amari  (Yume Nikki/Log.[in])
 * Phenomena Intervention Users such as Noel Vermillion or Hades Izanami (BlazBlue)
 * Lain Iwakura (Serial Experiments Lain)
 * Yaldabaoth (Persona 5)
 * Altair & Sirius  (Re:Creators)