I reworded it so it's more clear:
Imbue X (X, exile this card imbuing it to target creature you control. When the imbued creature dies, its controller may cast this spell without playing its mana cost. Imbue only as a sorcery.)
As a real mechanic, it would probably be overcosted to hell like Cipher. Alternatively, you'd wind up with dull cards like this:
Imbued Inspiration 3UU
Instant
Draw 2 cards.
Imbue 2U
Imbue X (X, exile this card imbuing it to target creature you control. When the imbued creature dies, its controller may cast this spell without playing its mana cost. Imbue only as a sorcery.)
As a real mechanic, it would probably be overcosted to hell like Cipher. Alternatively, you'd wind up with dull cards like this:
Imbued Inspiration 3UU
Instant
Draw 2 cards.
Imbue 2U