Hall of Heroes

If Gemstone Caverns is in your opening
hand and you're not playing first,
you may begin the game with
Gemstone Caverns in play with
a luck counter on it. If you do,
exile a card from your hand.
{t}: Add {c} to your mana pool.
If Gemstone Caverns has a luck counter
on it, instead add one mana of any color
to your mana pool.