If a player controls a battlefield with a hidden card, and all their units are removed during combat, do they lose control immediately or can they still use the hidden card?

Ruling: During combat, you maintain control of a battlefield even if all your units are removed, until combat fully resolves. This allows you to use your hidden card even without units present.

Sequence:

• Combat is initiated at a battlefield
• If all defending units are removed during combat (e.g., by a spell like Void Seeker)
• The controlling player still maintains control until combat finishes resolving
• The controlling player can still flip and use their hidden card
• Only after combat fully resolves does the player lose control if they have no units remaining

Nuances:

• Outside of combat, losing your last unit causes immediate loss of control and the hidden card is discarded
• This rule prevents exploits like using Ride the Wind to remove a unit, lose control, return the unit, and score again
• Hidden cards are tied to battlefield control, not directly to having units present (during combat)