On Rockfall Path (a battlefield that restricts unit placement), can you reveal hidden units like Sprite Call or Paaka Cub that would need to be played at an invalid location ('here')?

Ruling: You cannot reveal hidden units at Rockfall Path if their effect would require playing them at an invalid location. You must have a valid destination for a card to be played, so attempting to reveal these units would be an illegal action that must be taken back.

Nuances:

• This applies to cards like Sprite Call (which plays a unit "here") and Paaka Cub when the battlefield location restrictions prevent legal placement
• This makes Rockfall Path function as an anti-Teemo battlefield by preventing certain hidden unit reveals
• Hidden spells like Force of Fortune can still be hidden and revealed since they don't require unit placement