When Zhonya's Hourglass is played from hidden, does it only protect units at the battlefield where it was hidden, or can it protect units anywhere?

Ruling: When Zhonya's Hourglass is played from hidden, it protects the next unit that would die anywhere, not just at the battlefield where it was hidden.

Sequence:

• Zhonya's Hourglass is played from hidden to the battlefield
• A cleanup happens immediately after it resolves
• During cleanup, the gear is recalled to base (since gear cannot exist at battlefields)
• Zhonya's then functions normally from base

Nuances:

• Zhonya's does not target, so it is not restricted to a specific battlefield
• If a hidden gear had targeting ("When You Play Me" effects), it would have to target its battlefield
• Gear cannot exist at battlefields and is recalled during cleanup if it ends up there
• A cleanup happens after anything resolves/enters/moves