({T}: Add {W}.)
Mistveil Plains enters the battlefield tapped.
{W}, {T}: Put target card from your graveyard on the bottom of your library. Activate only if you control two or more white permanents.
A land card that produces white mana, even a Plains, normally has no color.
Once you activate Mistveil Plains’s last ability, it doesn’t matter if you lose control of some of your white permanents.