Trickery Domain: As bad as it seems?

[Tanarii]

So for Invoke Duplicity, just how 'real' is the illusion? Can it make noise? Does it shift about in place to mimic your movement within a 5' square? Can it pass through objects you can see through, like jail bars or a Wall of Force or a door with a keyhole? Can it be manifested off of the ground? Can it be MOVED off of the ground?

The utility of Invoke Duplicity can vary wildly depending on the answers to these questions. So it is a pretty DM-dependent effect.

So no more dependent than any spell or class feature, once you start trying to use it to do things not in the description.