If you play Zhonya's from hidden, can it affect units at any battlefield?

Ruling: Yes, Zhonya's affects all locations on the board even when played from hidden because its effect doesn't target, so it's not bound by hidden targeting restrictions.

Nuances:

• Even though gear played from hidden is typically recalled to base, Zhonya's would affect all battlefields regardless because it doesn't target
• Non-targeting effects are not restricted by hidden zone limitations