Ebondeath, Dracolich

• WOTC Official Reminder Textofficial rules
  Flash — You may cast this spell any time you could cast an instant.

• WWizards of the Coast2021-07-23
  Official Ruling
  Ebondeath, Dracolich's last ability cares only whether a creature not named Ebondeath, Dracolich died during the turn, even if Ebondeath, Dracolich wasn't in your graveyard when that happened. It doesn't matter if a creature named Ebondeath, Dracolich also died, and it doesn't matter what happens to the creature after it dies. For example, if the creature that died is a token or the creature card leaves the graveyard later in the turn, you can still cast Ebondeath, Dracolich.
• WWizards of the Coast2021-07-23
  Official Ruling
  Casting Ebondeath, Dracolich from your graveyard follows the normal rules for casting that card. You must pay its costs, and you must follow all applicable timing rules.
• WWizards of the Coast2021-07-23
  Official Ruling
  Ebondeath Dracolich cares what the creature's name was while it was last on the battlefield, not what it is in the graveyard. For example, if a creature with a different name becomes a copy of Ebondeath, Dracolich and then dies, you won't be able to cast Ebondeath, Dracolich from your graveyard.

Rulings via Scryfall