Legendary Land If Gemstone Caverns is in your opening hand and you're not playing first, you may begin the game with Gemstone Caverns on the battlefield with a luck counter on it. If you do, exile a card from your hand. {T}: Add {1} to your mana pool. If Gemstone Caverns has a luck counter on it, instead add one mana of any color to your mana pool.1
Illus. Martina Pilcerova
9/25/2006: After all players have decided not to take any more mulligans, players choose whether to put Leylines and/or Gemstone Caverns onto the battlefield, starting with the player who will be going first and proceeding in turn order. Each player may choose any number of Leylines and/or Gemstone Caverns. The cards are revealed and put onto the battlefield at the same time.
9/25/2006: If multiple Gemstone Caverns are put onto the battlefield before the game begins, the "legend rule" won't put them all into the graveyard until just before the first player gets priority during his or her first upkeep step. There's no opportunity to tap them for mana.
Time Spiral
(Rare)