(Centaur Cavern isn't a spell.)
At the beginning of your upkeep, Centaur Cavern deals 2 damage to target creature you control.
Sacrifice a land: You gain 1 life.
: 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.
