What does the keyword "Hidden" allow you to do during your turn?

The keyword "Hidden" in the context of the game allows you to hide the card at a battlefield you control. This can be strategically advantageous because it allows players to conceal their units or tactics, creating unpredictability in gameplay. Hidden units can often ambush opponents or provide surprise effects that might not be expected until they are revealed or activated later in the game. This mechanic can change the flow of a match, as it enables you to manage your battlefield presence and keep your opponent guessing about your potential moves or threats.

The other options do not accurately reflect the function of the Hidden keyword. Playing a card for free, doubling attack power, or drawing extra cards involve different mechanics and abilities and do not align with the concept of Hidden as a tactical gameplay element focused on concealment and surprise.