Play with the top card of your library revealed. You may cast instant and sorcery spells from the top of your library. Whenever you cast an instant or sorcery spell from your library, copy it. You may choose new targets for the copy.
Replicate {3}{U} Choose target permanent an opponent controls. Search that player's library for a card with the same name and put it onto the battlefield under your control. Then that player shuffles.
{3}: This artifact becomes a copy of target artifact until end of turn. {1}{U}{R}: This artifact becomes a copy of target artifact, except it has this ability.
"What is it? Um . . . what do you want it to be?" —Juzba, Izzet tinker
Exile target card that's an instant or sorcery from your graveyard. For each card exiled this way, copy it, and you may cast the copy without paying its mana cost. Exile Mizzix's Mastery. Overload {5}{R}{R}{R}
This spell can't be countered. Flying Whenever you draw a card, Niv-Mizzet deals 1 damage to any target. Whenever a player casts an instant or sorcery spell, you draw a card.
Defender Whenever you cast an instant or sorcery spell, this creature gets +3/+0 until end of turn and can attack this turn as though it didn't have defender.
Flip a coin. If it comes up heads, counter target instant or sorcery spell. If it comes up tails, copy that spell and you may choose new targets for the copy.