Doubling Chant

• WWizards of the Coast2011-09-22
  Official Ruling
  If you control a creature whose name has been changed by an effect (for example, a Clone that’s copying another creature), you’ll search for a card with the new name, not one with the original name.
• WWizards of the Coast2011-09-22
  Official Ruling
  If you control no creatures when Doubling Chant resolves, you may still search your library and you must shuffle your library.
• WWizards of the Coast2011-09-22
  Official Ruling
  The cards you find in your library must be creature cards. For example, you can’t put a land card onto the battlefield even if it has the same name as a land you control that’s also a creature (perhaps because of an ability of that land).

Rulings via Scryfall