How do Sphinx of Foresight and a discard effect on the first turn interact?
If a player reveals Sphinx of Foresight, that player gets to scry on their first upkeep even if the Sphinx gets discarded or exiled beforehand.

The Sphinx's ability creates a delayed triggered ability. That ability remains in the game no matter what happens to the Sphinx card. The ability only requires its controller's first upkeep to trigger, and its effect does not reference the Sphinx card as a prerequisite.


  603.7. An effect may create a delayed triggered ability that can do something at a later time. A delayed triggered ability will contain “when,” “whenever,” or “at,” although that word won’t usually begin the ability.