Gemstone Caverns | Magic: The Gathering
Formats Gemstone Caverns is Legal in
Official Oracle Text for Gemstone Caverns
: Add to your mana pool. If Gemstone Caverns has a luck counter on it, instead add one mana of any color to your mana pool.
Official Rulings for Gemstone Caverns
6/1/2011 : Your "opening hand" is the hand of cards you decide to start the game with after taking any mulligans.
6/1/2011 : After all players have decided not to take any more mulligans, if the starting player has any cards that allow actions to be taken with them from a player's opening hand, that player may take the actions of any of those cards. The starting player repeats this, taking all actions he or she wishes to, one at a time. Then each other player in turn order may do the same. After each player has exercised his or her option to take actions from his or her opening hand, the first turn of the game begins.
7/1/2013 : If multiple Gemstone Caverns are put onto the battlefield under a single player's control before the game begins, the "legend rule" won't put the extras into that player's graveyard until just before the first player gets priority during his or her first upkeep step. There's no opportunity to tap the extras for mana.