(Grassy Sea isn't a spell.)
When Grassy Sea enters the battlefield, sacrifice it unless you pay .
, : You may put a land card from your hand onto the battlefield.
: Add or to your mana pool.
Sacrifice Grassy Sea: Add or to your mana pool.
.
, 
: You may put a land card from your hand onto the battlefield.: Add 
or to your mana pool. or to your mana pool.
