Foreboding Ruins

• WWizards of the Coast2016-04-08
  Official Ruling
  If a Swamp or Mountain is entering the battlefield from your hand at the same time as Foreboding Ruins, you may reveal the other land to have Foreboding Ruins enter untapped.
• WWizards of the Coast2016-04-08
  Official Ruling
  You may reveal any land card with either or both of the appropriate subtypes. It doesn't have to be a basic land. For example, you could reveal Sunken Hollow from the Battle for Zendikar set to satisfy the ability of Foreboding Ruins.
• WWizards of the Coast2016-04-08
  Official Ruling
  If an effect instructs you to put Foreboding Ruins onto the battlefield tapped, it will still enter the battlefield tapped even if you reveal a land card from your hand.
• WWizards of the Coast2016-04-08
  Official Ruling
  Lands don't have a subtype just because they can produce mana of the corresponding color. Foreboding Ruins itself is neither a Swamp nor a Mountain, even though it produces black and red mana, so you can't reveal one to satisfy the ability of another.

Rulings via Scryfall