Void Grafter

Devoid is a characteristic-defining ability. “Devoid” means “This object is colorless.” This ability functions everywhere, even outside the game. See rule 604.3.

Flash is a static ability that functions in any zone from which you could play the card it’s on. “Flash” means “You may play this card any time you could cast an instant.”

Multiple instances of flash on the same object are redundant.