Murky Masquerade

As Murky Masquerade enters the battlefield you may exile two or more creatures you control face down, shuffle those cards, then put them into play face down as 2/2 creatures. If you don't, Murky Masquerade enters the battlefield tapped.
{t}: Add {u} or {b}.
{1}{u}{b}, {t}, Sacrifice Murky Masquerade: Turn all face down creatures you control face up.