Ephara's Dispersal

• WOTC Official Reminder Textofficial rules
  Surveil — Look at the top N cards of your library. Put any number of them into your graveyard and the rest on top of your library in any order.

• WWizards of the Coast2023-04-14
  Official Ruling
  The cost reduction ability of Ephara's Dispersal doesn't affect its mana cost or mana value. It affects only the total cost you pay. Specifically, its mana value is always 3.
• WWizards of the Coast2024-01-12
  Official Ruling
  When you surveil, you may put all the cards you look at back on top of your library, you may put all of those cards into your graveyard, or you may put some of those cards on top and the rest of them into your graveyard.
• WWizards of the Coast2024-01-12
  Official Ruling
  You perform the actions stated on a card in sequence. For some spells and abilities, you'll surveil last. For others, you'll surveil and then perform other actions.

Rulings via Scryfall