Tidal Store enters the battlefield tapped unless you pay .
: Add or to your mana pool.
Put Tidal Store on top of your library: Add to your mana pool.
: Tidal Store becomes a 2/1 blue and white Merfolk creature until end of turn. It's still a land.
.
: Add 
or 
to your mana pool.
to your mana pool. : Tidal Store becomes a 2/1 blue and white Merfolk creature until end of turn. It's still a land.
