When hiding a card with the Hidden ability, do you need to recycle a rune or just exhaust (tap) it to pay the 1 Power cost?

Ruling: To hide a card with the Hidden ability, you must recycle a rune (put it back in your deck) to pay the 1 Power cost, not just exhaust (tap) it.

Nuances:

• Exhausting runes is for gaining Energy (numbers in black circles), not Power
• Power is gained by recycling runes
• Hidden cards cannot be played (flipped up) on the same turn they are hidden
• When flipped from hidden as a reaction, the card goes on the stack like any other reaction
• Cards must be hidden at a battlefield you control, not at your base
• When played from hidden as a reaction, cards must target the battlefield they are hidden at