If a unit with hidden Tideturner at battlefield A gets +1 Might from Mask of Foresight when opponent attacks, then during showdown uses Ride the Wind to move to battlefield B and reveals Tideturner to swap back to battlefield A, does the unit get another +1 Might from Mask of Foresight? Also, when is battlefield B scored?

Ruling: The unit does NOT get another +1 Might from Mask of Foresight when it returns to battlefield A. Attack and defend triggers only trigger the first time a unit gains the attacker or defender designation. When Tideturner is revealed at battlefield B, it does get +1 Might from Mask of Foresight as it becomes a defender alone at that battlefield.

Sequence:

• Play Tideturner at battlefield B
• Tideturner WYPM goes on chain first, then Mask of Foresight trigger
• All players pass
• Tideturner gets +1 Might
• All players pass
• Tideturner and unit swap positions
• The current combat at battlefield A must fully resolve before any showdown at battlefield B starts
• If you still control units at battlefield B at the end of that showdown, you will score

Nuances:

• You don't lose control of a battlefield until the end of combat, so hidden cards stay even when units move away during combat
• If this interaction happened outside of a showdown, you would lose control of the battlefield when the unit moved away