How does the hidden mechanic work in Riftbound, specifically regarding where hidden cards can be placed and what they can target?

Ruling: Hidden cards are placed at a battlefield (only one per battlefield). You pay any color power to hide a card, then pay 0 to play it at that battlefield for its hidden cost. You cannot activate a card the same turn you hide it.

Sequence:

• Pay any color power to hide a card at a battlefield
• Pay 0 to play the hidden card at that battlefield (on a later turn)
• The card activates with its hidden cost

Nuances:

• Hidden cards can only be placed at battlefields, not at base
• Only one hidden card allowed per battlefield
• Hidden cards cannot be activated the turn they are hidden
• All effects of hidden cards only affect the battlefield where they are hidden
• Hidden cards can only target units at the same battlefield when played from hidden