Form of the Mulldrifter

• WWizards of the Coast2019-11-12
  Official Ruling
  If Form of the Mulldrifter leaves the battlefield, any Mulldrifters on the stack or battlefield remain Mulldrifters.
• WWizards of the Coast2019-11-12
  Official Ruling
  Mulldrifter is a 2/2 blue Elemental creature with mana cost and the abilities flying, “When Mulldrifter enters the battlefield, draw two cards,” and evoke .
• WWizards of the Coast2019-11-12
  Official Ruling
  Evoke means “You may cast this spell by paying rather than its mana cost.” and “When this permanent enters the battlefield, if its evoke cost was paid, its controller sacrifices it.”
• WWizards of the Coast2019-11-12
  Official Ruling
  A creature card cast this way has Mulldrifter’s characteristics until it leaves the battlefield or leaves the stack other than by resolving. These characteristics are copiable values of that object.

Rulings via Scryfall