How does Zhonya's Hourglass activation cost work when using its hidden effect, and what is the orientation of the face-down card?

Ruling: When playing Zhonya's Hourglass normally, it costs 2 Runes and is placed readied in your base. When using the hidden effect, you only pay power to hide it, then can play it for free from hidden (not an additional 3 Runes total).

Sequence:

• To play normally: Pay 2 Runes, place readied in base
• To use hidden effect: Pay power to hide it, then play for free from hidden

Nuances:

• The face-down card orientation (horizontal or vertical) does not matter