Cipher

As an additional cost to cast this spell, exile
an instant or sorcery card with mana value X from your hand. Its identity must also not include colors other than black and/or blue. This card becomes a copy of the exiled card with cipher. (Cast it without paying its mana cost, then you may exile this spell card encoded
on a creature you control. (The encoded card is a copy of the card you exiled in addition to casting this spell.))