Niv-Mizzet, the Omniscient

As an additional cost to cast Niv-Mizzet, the Omniscient, you may sacrifice 3 artifacts. If you do, it has flying, hexproof, and disassimilate X
Each players plays with his or her hand and the top card of their library revealed. You may cast revealed cards, and you may spend mana as though it were mana of any color to cast that spell.
{u/r}{u/r}, sacrifice X artifacts, {t}: Choose a player. You Scry X that players library.