1) I presume, that I have to play a card (attack) from my hand and only then I can use this hammer. Can I use the hammer (roll) first to see, what card(s) I have to use to accomplish the test?
2) On the card there is no restriction as to the number of rolls/uses I can have. Does that mean, that if I am lucky enough I can boost the attack multiple times? With few diamonds/rerolls I could get easily a lot of REDs.