With Theros having a minor "scry" theme, I figured it would be useful to tell you how to put a card on the bottom of your library during testing.
On the Mac, you want to hold down "command", and drag the card to the deck icon.
On the iPad, there is a "To library top" and "To library bottom" option in the bottom right corner.
On the other devices, you can swipe left with two fingers on a card to put it on the bottom of your library.
Good luck, and may you never need to scry to the bottom in real life!