Noxus Saboteur

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Hidden

On your turn in an open state, pay 1 Power of any domain to hide the card face-down at a battlefield you control that has no card hidden there.

From the next turn—including your opponent's—you can play it as a Reaction, ignoring its base cost. Additional costs still apply. It stays hidden there only while you control that battlefield. A hidden unit or Gear is played there; targets normally must be there too, unless the card explicitly requires a target elsewhere. You can instead play the card normally without hiding it.