If a unit at a battlefield is targeted by a spell and moved to the other battlefield in response, does the spell fizzle?

Ruling: Spells never fizzle. Only the part of the spell that relies on the target fails to resolve if the target becomes invalid.

Nuances:

• If the spell targets "something at Battlefield" (any battlefield), moving the unit to the other battlefield keeps the target valid and the spell resolves normally
• If the spell targets a specific battlefield then targets something there, or if the spell was played from hidden, moving the unit to a different battlefield makes the target invalid
• Moving the targeted unit from a battlefield to the base makes the target invalid