Hidden Herd

• WWizards of the Coast2004-10-04
  Official Ruling
  Does not trigger on lands put onto the battlefield by a spell or ability.
• WWizards of the Coast2004-10-04
  Official Ruling
  When it turns into a creature, it is no longer an enchantment.
• WWizards of the Coast2008-08-01
  Official Ruling
  A noncreature permanent that turns into a creature can attack, and its abilities can be activated, only if its controller has continuously controlled that permanent since the beginning of their most recent turn. It doesn't matter how long the permanent has been a creature.

Rulings via Scryfall