Selune, Our Lady of Silver

{2}, {t}: Create a 1/1 white Owl creature token
with flying.
As long as your devotion to white and blue is less
than seven, Selune isn't a creature.
Whenever you cast a creature spell, sacrifice a
creature you control. Whenever a creature you
control dies, you may play a creature card from
your hand without paying its mana cost. This
ability only triggers once per turn.