So, I've been thinking about how I could go around to tweaking my izzet deck to play on FNMs, and this is my updated list for now:
Lands (23)
2 Mutavault
4 Steam Vents
4 Izzet Guildgate
13 Mountain
Creatures(16)
3 Frostburn Weird
3 Young Pyromancer
3 Guttersnipe
3 Spellheart Chimera
1 Chandra's Phoenix
1 Boros Reckoner
2 Purphoros, God of the Forge
Spells (21)
4 Magma Jet
4 Lightning Strike
4 Mizzium Mortars
4 Izzet Charm
2 Turn//Burn
1 Hammer of Purphoros
2 Steam Augury
Sideboard
2 Pithing Needle
2 Electrickery
2 Ratchet Bomb
2 Gainsay
1 Negate
1 Cyclonic Rift
1 Mindsparker
1 Turn//Burn
3 Syncopate
Since the deck barely requires any blue mana to run, I decided to remove all islands and play more red-based cards. I'm not exactly sure how good Purphoros is going to be, but I think it has great synergy with Young Pyromancer, and has the possibility of becoming a creature (I'll probably need more Phoenixes and/or Reckoners, though). The Hammer's an experimental card, since on paper it works well with the god as well as my Pyromancer's tokens, while giving me some late-game reach and making Spellheart Chimeras quite deadly out of nowhere.
I ended up cutting a Chimera and a Guttersnipe for more defensive spells to help the deck survive against aggro decks, and added Mutavaults after realizing how well they worked on most match-ups. After cutting Opportunity to lower my curve and allow the deck to function with no Islands, I also went down to 23 lands (from 24).
I've devoted many sideboard slots to fare better against control decks, but I fear that by heavily leaning towards creature-centric match-ups in my main-deck, the deck's chances against control on game one might be wholly unacceptable.
The mono-black match-up seems like it could be a real issue for the deck, with Thoughtseize picking apart my relevant cards and their spot removal taking care of my few relevant creatures, as well as them siding in Shrivel to wipe my elemental tokens along with the Pyromancer...