The Night Swamp

When The Night Swamp enters the battlefield
put a swamp you control on top of your library.
If you are playing and it's dark out or raining
you may tap this for 3 black mana.
If you are playing and it's not dark or raining
you can tap this for 3 blue mana.
Night or day, swamp or iland, who knows what it
is now.