When Flat Sea enters the battlefield, sacrifice it unless you pay .
: Add or to your mana pool.
: Flat Sea becomes a 1/1 white and blue Cleric creature with flying until end of turn. It's still a land.
.
: Add or 
to your mana pool.
: Flat Sea becomes a 1/1 white and blue Cleric creature with flying until end of turn. It's still a land.
