The changes are quite nice as well. May you don't need the whole playset of niv-mizzet, 'cause it's expensive (mana-wise) and a legendary. I like adding the
glint-horn buccaneer! You got 67 cards in the main, that changes the land-nonland probability too much I guess. You can muck out the counterspells and of course some of the lightning-cards and may adding
thrill of possibility or catharic union for the Buccaneer and
improbable Alliance. If you like the
Benthic Biomancer, I can give you the 2 Cards missing for the full playset and you can add
zameck guildmage as well, working great with it. You should stay on 24 Lands in 60 Cards vor this deck.
regards