: Add 
. If Gemstone Caverns has a luck counter on it, instead add one mana of any color.Gemstone Caverns can accelerate a starting hand when you are not the starting player. If it is in your opening hand, you may begin with it on the battlefield with a luck counter by exiling another card from your hand. With that counter it produces any color; without it, the ordinary mana ability produces colorless.
That opening can let a blue deck leave interaction available earlier or help cast an engine before its normal schedule. The exiled card is a real resource cost, so choose around the spells the hand still needs. Drawing Caverns later does not create the opening-hand opportunity, and simply putting it into play during the game does not grant a luck counter.
Plan the turn around both the amount of mana available and the colors each spell requires. A hand containing Sol Ring can have plenty of total mana while still struggling with colored symbols. Keep reliable lands alongside specialized sources, and sequence the source that establishes a missing color before committing resources to a payoff that depends on it.
Keep the whole opening hand in view before exiling a card. Losing a necessary land or the only payoff can erase the benefit of starting ahead. The land is also legendary, so additional copies or copy effects require attention to the legend rule rather than automatically becoming independent extra sources.
