Commune with Lava

• WWizards of the Coast2015-02-25
  Official Ruling
  Playing a card this way follows the normal rules for playing the card. You must pay its costs, and you must follow all applicable timing rules. For example, if one of the cards is a creature card, you can cast that card only during your main phase while the stack is empty.
• WWizards of the Coast2015-02-25
  Official Ruling
  Under normal circumstances, you can play a land card exiled with Commune with Lava only if you haven't played a land yet that turn.
• WWizards of the Coast2015-02-25
  Official Ruling
  The cards are exiled face up.
• WWizards of the Coast2015-02-25
  Official Ruling
  Any cards you don't play will remain exiled.

Rulings via Scryfall