When Tideturner is hidden, can it be played into the base to switch with another friendly unit on a battlefield, or must it be played at the battlefield where it was hidden?

Ruling: Tideturner can only be played at the battlefield where it was hidden, not into the base to switch with units on other battlefields.

Nuances:

• Hidden units must be played at the specific battlefield where they were hidden
• Tideturner's ability to switch with friendly units does not override the hidden placement restriction