Thurid, Mare of Destiny

• WOTC Official Reminder Textofficial rules
  Lifelink — Damage dealt by this creature also causes you to gain that much life.

• WWizards of the Coast2024-11-08
  Official Ruling
  As a copy of a permanent spell resolves, it's put onto the battlefield as a token rather than putting a copy of the spell onto the battlefield. The rules that apply to a permanent spell becoming a permanent apply to a copy of a spell becoming a token.
• WWizards of the Coast2024-11-08
  Official Ruling
  The token that a resolving copy of a permanent spell becomes isn't "created." Abilities that refer to a token being created won't interact with the copy resolving.
• WWizards of the Coast2024-11-08
  Official Ruling
  Thurid's triggered ability doesn't trigger if a Pegasus, Unicorn, or Horse creature is put onto the battlefield without being cast.
• WWizards of the Coast2024-11-08
  Official Ruling
  Thurid's triggered ability and the copy it creates will resolve before the spell that caused it to trigger. They resolve even if that spell is countered or otherwise leaves the stack without resolving.
• WWizards of the Coast2024-11-08
  Official Ruling
  Thurid's triggered ability will copy only creature spells, not noncreature kindred spells, even if those spells have the Pegasus, Unicorn, or Horse types.

Rulings via Scryfall