(Moonring Cavern isn't a spell.)
Moonring Cavern enters the battlefield tapped.
Moonring Cavern is indestructible. (Destroy effects and lethal damage don't destroy it.)
: Add to your mana pool.
: Add or to your mana pool. Each opponent gains 1 life.
: Add 
to your mana pool.: Add 
or 
to your mana pool. Each opponent gains 1 life.
