When Khalni Gem enters the battlefield, return two lands you control to their owner's hand.
: Add two mana of any one color to your mana pool.
10/1/2009 If you don’t control any lands by the time Khalni Gem’s triggered ability resolves, nothing happens. If you control just one, you’ll have to return it to its owner’s hand. Khalni Gem isn’t affected in either case.