Orias, Sovereign of Stars

As Orias, Soveriegn of Stars comes into play,
choose either even or odd. Cards you own
with a converted mana cost that is the same
as the option you chose cost {1} less to cast.
{2}{u}, {t}: Destroy target creature. Its controller
reveals cards from the top of their library until
they reveal a nonlegendary creature card. That
player puts that card onto the battlefield and the
rest on the bottom of their library in a random
order.