(Slagheap Flagstones isn't a spell.)
Slagheap Flagstones enters the battlefield tapped unless you pay .
Sacrifice a land: You gain 1 life.
: Add or to your mana pool.
Put Slagheap Flagstones on top of your library: Add to your mana pool.
.
: Add 
or 
to your mana pool. to your mana pool. 
