When playing "Guards!" from hidden, must the sand soldier be played to the battlefield, or does the battlefield restriction only apply to targeting effects?

Ruling: The battlefield restriction applies to both targeting effects and selecting locations when playing units as part of a spell/ability. The sand soldier must be played to the battlefield when "Guards!" is played from hidden.

Nuances:

• The battlefield restriction is not limited to targeting; it also affects where units can be placed when played as part of spell/ability resolution