What happens when Here to Help is played from hidden (via Rockfall Path) if the player doesn't control a battlefield where units can be played?

Ruling: Here to Help whiffs because there is no legal destination to play the unit. The "can't" restriction from the battlefield overrides the "can" permission from Here to Help.

Sequence:

• Rockfall Path allows Here to Help to be played from hidden
• Here to Help attempts to play a unit
• No valid battlefield exists where units can be played
• Here to Help resolves but whiffs (no unit is played)

Nuances:

• Here to Help uses "may" language, so it can resolve even when the effect cannot be executed
• The "can't beats can" principle applies: battlefield restrictions prevent the unit from being played even though Here to Help would normally allow it