I'm on my phone, sorry for not linking all cards. 4x Mutavault in a Boros deck is greedy, I'd go 2x max and cut the guildgates for temple of malice. Boros works best when you run one of the colors and splah a little of the other. You have this with red as the main and Brimaz sticks out. I'd cut him for 2 more Chandra's Phoenix . They're faster and evasive, 14 cards to recur it. Flame-Wreathed Phoenix is an option as well, either form is great in this deck. I like Aurelia, the Warleader as a 1x but better as a 2x with 25 lands or drop her and go to 24 lands.

I like this deck. Big Boros has all the tools to be a tier 1 deck. Playing more burn like you are will improve your match ups vs U/W Control and MUD.

Thanks Rasta_Viking29 you're not the only one who suggested removing Brimaz, last week when I ran him I had one in the main and one in the side. I know he doesn't fit the theme, but there's just something about him that I like. The person who said to remove him wanted more Chandra's Phoenix too with even more burn, but I feel like I need something with a little more meat. What I like about Brimaz is he survives blight's -3/-3 and spawns tokens that can shut down a desecration demon. In that respect I like him more then Boros Reckoner when against MBD orB/W midrange, both of which are a thing at my store. The other Phoenix isn't a bad idea, and if Brimaz does come out its for a creature in the 3-4 CMC drop. A 2nd Aurelia, the Warleader is something I'm toying with, but with 4 Stormbreath Dragon s already mainboard, I wonder whether that's too many high CMC drops. Last week I had 1x Elspeth in the main and 1 in the side with Aurelia, but this is how I've repositioned things. Don't have the temple of malice yet, but haven't had msna problems with the mutavaults either. I don't know. Let me ask you this, if I were to change 2 cards to improve my matchup against MBD and B/W midrange, what would you suggest?

Cut that Wear / Tear for some Revoke Existence (yeah get some of those in the side, i suggest 3, maybe cut Chandra, Pyromaster and Warleader's Helix )

+1 for burn control! And for throwing in Gorgon Heads :-D Equip to Reckoner...OMG, insane.

Maybe cut some of the odd one-ofs like Wild Ricochet and Chandra's Outrage to turn up the scry with 4x Magma Jet . Ditto in the sideboard, who needs Mizzium Mortars with this much kill, instead go up on Pithing Needle and Purpy for control. Maybe Ricochet could live in the board for that purpose. Or Skullcrack vs. Sphinx's Revelation ?

Fine work :D Love that Phoenix comes back over and over...

i would Lightning Strike for Magma Jet

Updated description. Thinking on some of the synergies. Feedback would be appreciated!

To be honest, I'm not really sure about the new direction you were mentioning with shrapnel blast and ensoul artifact. I mean, take godsend for example. It just seems like a waste of its incredible effect to turn it into a creature that can be taken out with a vast suite of cards from black or blue, and even some from red for a 2 for 1. getting godsend equipped is practically game, especially to a boros reckoner, I just don't see it being worth it to blow it up or make them able to just chump block it. I'd gladly give an opponent a 5/5 to get rid of having to deal with a game changer like godsend. I realize that's only 1 artifact out of the deck, but I wouldn't put it on gorgons head really either. It's not really that bad on gorgon's head, but in my opinion making it a creature makes izzet staticaster almost useless in this deck. It's like a strictly worse version of sylvan caryatid with a higher cost. though truly, I think izzet staticaster is really more of a sideboard card to put in against agro or token decks to begin with.

The only other thing I'm wondering is why the sideboard for boros charm? they are so much more versatile for a deck like this. Imagine that scenario you mentioned, flashing in dictate of the twin gods and swinging for double damage, then suddenly pulling double strike out of thin air for the win in a single hit? that seems a lot more of a reliable combo then channeling through boros reckoner. Also 4 to the face seems a lot better then 5 to the face after you sac an artifact.

All in all, it's a long-winded way of suggesting I'd go with:

Out:

-4 Izzet Staticaster

-3 Shrapnel Blast

-1 Gorgon's Head

-1 Ensoul Artifact

In:

+4 Boros Charm (completely broken card, versatile enough for any deck flying the R/W flag)

+2 Fiendslayer Paladin ('cause removal be damned)

+2 Spark Trooper (combat tricks and trample FTW. "I gain 12 life and you lose 6 life and your desecration demon" how discouraging is that? lol)

+1 Godsend (Pretty much game if it resolves.)

That's my 2 cents at least, hope it helps!