Can a hidden unit (like Tideturner) be played to a location other than the battlefield where it was hidden?

Ruling: No, the unit must be played at the battlefield where it is hidden.

Nuances:

• When a unit is hidden at a battlefield, all choices (including location) must only be picked from among valid targets at the battlefield associated with that Facedown Zone
• The rules for hidden will likely be reworded to better reflect this intent