Kasai, Queen of the Flame

When Kasai, Queen of the Flame enters the field, you may choose a color other than red. All creatures of the chosen color get -3/-3. If Kasai were to leave the field, destroy all creatures of the chosen color. If she were to die, burn all lands. (They become basic mountains.)
Kasai is invulnerable to attacks from a red source.
I don't think all fire is bad. After all, I'm keeping you warm, aren't I?