Linvala, Keeper of Silence

• WWizards of the Coast2016-06-08
  Official Ruling
  Activated abilities contain a colon. They’re generally written “[Cost]: [Effect].” Some keywords are activated abilities and will have colons in their reminder text.
• WWizards of the Coast2017-03-14
  Official Ruling
  No abilities of creatures your opponents control can be activated, including mana abilities.
• WWizards of the Coast2017-03-14
  Official Ruling
  Linvala’s last ability affects only creatures on the battlefield. Activated abilities that work in other zones (such as bloodrush or unearth) can still be activated. Triggered abilities (starting with “when,” “whenever,” or “at”) are unaffected.

Rulings via Scryfall