In the eldritch invocation “One with Shadows”, it is stated that the player is invisible in a dim location until an action or reaction is used. Since movement is not an action, could the player use just movement on a turn or outside of combat and still remain invisible?
3 Answers
Movement breaks the invisibility of "One With Shadows".
The Eldritch Invocation "One With Shadows" states:
When you are in an area of dim light or darkness, you can use your action to become invisible until you move or take an action or a reaction.
Emphasis mine.
If you move, whether on your turn or outside of combat, the invisibility ends.
Movement also ends One with shadows
From the description of the ability (emphasis mine)
(...) to become invisible until you move or take an action or a reaction.
Movement ends One With Shadows explicitly
When you are in an area of dim light or darkness, you can use your action to become invisible until you move or take an action or reaction.
Movement explicitly causes you to become visible.