If I have a unit at a battlefield with a hidden Zhonya's, and my opponent recalls my unit to base (causing me to lose control of the battlefield), what happens if I play the Zhonya's in response?

Ruling: You can react with the hidden Zhonya's before the recall resolves. The Zhonya's will be recalled back to base along with the unit, but it is still meant to affect only units at that battlefield.

Sequence:

• Opponent plays spell to recall your unit
• You can react with hidden Zhonya's before the recall resolves
• Zhonya's activates at the battlefield
• When gear are at a battlefield during recall, they are recalled back to base
• Zhonya's goes back to base once everything resolves

Nuances:

• If you lose control of a battlefield without reacting, hidden cards go straight to the trash
• It is not yet clear in the rules whether the Zhonya's will be able to save units at other locations after being recalled to base - this will be clarified in the future