Knowledge and Power

Oracle Text

Whenever you scry, you may pay 2. If you do, Knowledge and Power deals 2 damage to any target.

Card Rulings

4/26/2014 Knowledge and Power’s ability triggers only once each time you scry, no matter how many cards you look at.
4/26/2014 You choose the target of the ability as it’s put on the stack. You choose whether to pay as it resolves. You can pay only once each time you scry.