When you reveal Guards! does it go to the battlefield or base?

When you play Guards! by revealing it from its hidden position, the Sand Soldier token it creates must be played at the same battlefield where the Guards! card was hidden. You cannot play it to your base.

This is a firm requirement supported by multiple rules and FAQs:

• Rule 811.1.d.3: "If a hidden spell or a play effect of a hidden permanent causes you to play a unit, you must choose to play that unit at that battlefield [where the card was hidden]."
• RiftJudge FAQ #9273: Explicitly states, "No, you cannot play the Sand Soldier token created by Guards! to your base."
• RiftJudge FAQ #9517: Reaffirms that the token must enter play at the same battlefield where the Guards! card was hidden.