Sandstone Oracle

• WWizards of the Coast2020-11-10
  Official Ruling
  You choose an opponent while Sandstone Oracle's ability is resolving. No player may take actions between the time you make this choice and the time you draw cards.
• WWizards of the Coast2020-11-10
  Official Ruling
  To draw cards equal to the difference, first determine how many cards you'll draw, then draw that many cards, as modified by replacement effects. For example, if you have two cards in hand and the chosen opponent has five, Thought Reflection will cause you to draw six cards instead of three.

Rulings via Scryfall