Fox-Fire

Keywords in this card's text

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.

Action

Also lets you play the card or activate the ability in an open Showdown, including on your opponent's turn. Its normal timing still works.

Action alone does not let you respond to a spell or ability waiting on the chain.

How Focus and Priority decide when Action and Reaction can be used