Though hasty, this is an interesting one. Yes, Niv-Mizzet is pricey, but everything else is cheap. Of course, 13 cards have an X in the title (hence the name), but they have Goblin Electromancers backing them up. Because I have this color combo, I had to go with Riverfall Mimic to pound away unblockably, and the deck contains 23 other cards to trigger it (not counting the 2nd, 3rd, and 4th copies of the mimic itself). It generally won't make for a great fight, but the damage dealing with instants and sorceries will compensate to some degree. With a 20/17/1/0/0/2 curve averaging 1.73, it would average 1.50, but for the two copies of Niv-Mizzet.