What happens when a spell targets a unit at a battlefield and that unit moves to a different battlefield before the spell resolves?

Ruling: If a spell was played from hidden and targets a unit at a battlefield, it will not resolve successfully if the unit moves to a different battlefield. If the spell was played from hand, it will still resolve successfully as long as the unit is still at any battlefield.

Nuances:

• The distinction depends on whether the spell was played from hidden or from hand
• Moving to base would cause the spell to fail in both cases
• Moving to a different battlefield only causes failure for spells played from hidden