If Zhonyas is hidden at a battlefield and you flip it in response to Charm trying to move your unit away from that battlefield, does Zhonyas protect the unit?

Ruling: No, Zhonyas cannot protect the unit in this case. When you flip Zhonyas in response to Charm, your unit dies at the other battlefield and cannot be saved by Zhonyas because Zhonyas can only protect units at the battlefield where it was hidden.

Nuances:

• This is the official ruling from Riot, though the exact mechanical justification is not yet clear in the current rules
• When Zhonyas is flipped, it gets recalled to base (since gear can't be on battlefields), but it remains tied to its original battlefield for protection purposes
• The timing of when Zhonyas stops being tied to its battlefield is currently an unanswered question that will be clarified in an updated Comprehensive Rules Document