Selfless Glyphweaver // Deadly Vanity

• WWizards of the Coast2021-04-16
  Official Ruling
  As Deadly Vanity resolves, you choose which creature or planeswalker you are saving. Once the choice is made, there is no window for players to respond before the rest of the creatures and planeswalkers are destroyed.
• WWizards of the Coast2021-04-16
  Official Ruling
  You must choose a creature or planeswalker if there is one on the battlefield.
• WWizards of the Coast2021-04-16
  Official Ruling
  Because Deadly Vanity does not target the permanent you choose to save, you may choose creatures with hexproof or protection from black.
• WWizards of the Coast2021-04-16
  Official Ruling
  You may choose any creature or planeswalker, even one controlled by an opponent.
• WWizards of the Coast2021-04-16
  Official Ruling
  You may activate Selfless Glyphweaver’s ability only if Selfless Glyphweaver is on the battlefield. Only creatures you control as that ability resolves will gain indestructible. Creatures that come under your control later in the turn will not.

Rulings via Scryfall