Users can create, shape, and manipulate reality, the sum or aggregate of all that is real or existent within a system, just by thinking about it; while weaker users are limited to what is already considered "real," stronger ones can make changes from nothing. Depending on the power of a reality warper, they may alter something as tangible as physics and the universe to something inconceivable like logic.
The way the power actually works is when the user controls the very existential state of anything depending on their proficiency, regardless of whether or not the entity in question is an object or subject, among so many or most others depending on their power scale. It can range from transmogrifying objects or subjects into something different, altering the laws of reality, logic, and physics, creating things out of thin air, to even outright erasing it on the spot
Any and all scientific or natural laws such as biology, causality, physics, or even time, – they no longer apply to the user. Yes, for all intents and purposes, a Reality Warper can literally do anything they want. Anything.
The key issue here is how far one can take this. A character with a mild form of this power may be able to fly by negating the effect of gravity on himself/herself. A major case of this may be able to hiccup and accidentally tear the space-time continuum. High-end Reality Warpers tend to be related to the setting itself, such as being one of the sentient cosmic laws. For the really high-end ones, see The Omnipotent.
Absolute Will - In most of the cases, users require nothing but their will alone to alter/control reality.
Nigh-Omnipotence/Logic Manipulation High level reality warpers can not only perform inconceivable acts beyond logic, but can basically do almost anything they want