Eloise, Nephalia Sleuth

• 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.
• WOTC Official Reminder Textofficial rules
  Investigate — Create a Clue token. It's an artifact with ", Sacrifice this artifact: Draw a card."

• WWizards of the Coast2021-09-24
  Official Ruling
  If you sacrifice a Clue token, Eloise's last ability will trigger in response. You'll surveil before drawing the card.
• WWizards of the Coast2021-09-24
  Official Ruling
  If you create a token that's a copy of Eloise and both are legendary, you will choose either the token or the original Eloise to keep and put the other into the graveyard. This is not the same as sacrificing it. Putting the token into the graveyard won't cause nontoken Eloise's last ability to trigger.
• WWizards of the Coast2021-09-24
  Official Ruling
  Eloise's last ability triggers whenever you sacrifice any token for any reason, not just whenever you sacrifice Clue tokens.

Rulings via Scryfall