Lightform

Some previous Magic sets feature double-faced cards, which have a Magic card face on each side rather than a Magic card face on one side and a Magic card back on the other. If a double-faced card is manifested, it will be put onto the battlefield face down. While face down, it can't transform. If the front face of the card is a creature card, you can turn it face up by paying its mana cost. If you do, its front face will be up. Although a double-faced card can enter the battlefield face down, one already on the battlefield can't be turned face down.

If an effect tries to return a face-down creature to the battlefield after it leaves (such as Aminatou's second ability or Adarkar Valkyrie's delayed triggered ability), that effect returns the card face up. If it tries to put an instant or sorcery card onto the battlefield this way, that card remains in its current zone instead.

Because the permanent is on the battlefield both before and after it's turned face up, turning a permanent face up doesn't cause any enters-the-battlefield abilities to trigger.