Mag, Mistress of Identity

You may spend mana as though it were mana of
any type to activate activated abilities.
{x}{x}{u}{b}: Mag, Mistress of Identity becomes
a copy of target creature card in a graveyard
with converted mana cost X, except its name is
Mag, Mistress of Identity, it's legendary in
addition to its other types, and it has this ability.
"Identities are flexible, and so is your neck,
hopefully."