Can Fox Fire target cards at different battlefields, or must all targets be at the same battlefield?

Ruling: When played from hand, Fox Fire can target units at any one singular battlefield. When played from Hidden, it can only target units at the battlefield where it was Hidden.

Sequence:

• If played from Hidden: Can only target units at the battlefield where Fox Fire was Hidden
• If played from hand: Can target units at any one battlefield (but all targets must be at the same battlefield)

Nuances:

• The card says "at a battlefield" (singular), not "at battlefields" (plural), which means all targets must be at the same battlefield even when played from hand
• Hidden has a general rule that cards played from Hidden must target things at the place where they were Hidden