Creatures - 12
3 Chandra's Phoenix
1 Chandra's Spitfire
1 Prodigal Pyromancer
2 Obsidian Fireheart
2 Fire Servant
1 Magma Phoenix
2 Inferno Titan
Other Spells - 24
1 Earthquake
2 Flame Slash
1 Lightning Bolt
1 Red Sun's Zenith
1 Rain of Embers
3 Searing Blaze
4 Searing Spear
2 Flamebreak
2 Flames of the Firebrand
1 Chain Reaction
4 Chandra's Outrage
1 Beacon of Destruction
1 Fireblast
Lands - 24
24 Mountain
General Strategy: Burn your opponent's early creatures. Don't be afraid to take a little early damage if it means you can gain card advantage with Flamebreak, Earthquake, Flames of the Firebrand, etc. Don't use your searing spears on your opponen'ts life total in the early game. Searing Blaze, Flamebreak, and Chandra's Outrage can put a nice dent in your oppoent's life total early on, which Inferno Titan or something else can clean up later. Time for some individual card choices, followed by why I excluded some cards:
Red Sun's Zenith - I like the fact that it exiles the creature you use it on, and it shuffles itself back into your deck to be used later. I only included one because it's kind of a more late-game spell. You'd want to use your other burn cards first, and maybe finish your oppoent off with this later, or save it for a really deadly creature. This deck already has a lot of 4-6 mana cost cards, and while the Zenith can be played for less, I feel that it would overall hurt the mana curve of this deck. This deck likes to use more efficient burn spells early on (Searing Blaze, Flames of the Firebrand, Flamebreak, etc) which can damage the opponent in addition to the creature, or create card advantage (or both). This puts the Zenith as a more of a late game card, which is why I only chose to put one in my build, but I could certainly see justifying two.
Rain of Embers - A great, and underestimated mini-sweeper. A lot of decks have a lot of 1 toughness creatures, and this is another way to get card advantage from them. This rips apart Yeva's shenanigans of bouncing back Wood Elves and Elvish Visonary to gain card advantage, and it pings your opponent to boot. Worst case senario, this card should be a 1-for-1 trade, as most decks have at least 1 creature that has 1 toughness. It has late game uses too, being able to cheaply trigger Chandra's Phoenix and Spitfire.
Searing Blaze - make sure you get the landfall to get the maximum potential out of this. Kill a creature, and dent your oppoent's life total.
Chandra's Phoenix - Another great card. Combos nicely with things like Searing Blaze, Flamebreak, and Outrage. Haste and flying can put pressure on your opponent early, and recurring it is always nice, since it doesn't take mana to return from your graveyard to your hand (well, it does, but in an indirect way).
Chandra's Spitfire - pretty obvious include. Can put threating pressure on your oppoent very quickly. Also great with Searing Blaze, Flamebreak, Outrage, etc. since those cards remove blockers and pump the spitfire at the same time.
Flamebreak - Only real downside to this is that it damages you too, but that's only an issue if you're low on health. Otherwise, awesome board sweeper, and hits your oppoent at the same time. Great Synergy with Chandra's Phoenix/Spitfire. Anyone noticing a pattern yet?
Flames of the Firebrand - Generally, I try to use this to gain card advantage, even if it means taking a bit of early damage.
Prodigal Pyromancer - I love pingers in the DotP format. It just seems that every deck has 1 toughness creatures, some of which you really want dead (like the creature in Garruk's deck that can make creatures fight each other).
Chandra's Outrage - Not much to say which hasn't already been said. Kill a creature and dent your oppoent's life total. Synergy with Phoenix and Spitfire.
Obsidian Fireheart - great power/toughness for 4 mana. You can also use his ability to put a clock on your opponent. One of the variety of finishers this deck has, which is good because you don't want Inferno Titan to be your only threatening creature that your opponent saves all their removal for.
Fire Servant - Another "kill me now or lose" card to your opponent. This turns any burn spell into deadly force, for both your opponent and their creatures. And this deck has loads of burn spells.
Magma Phoenix - more air power, can act as a sweeper, and you can recur it if the game goes long and you need more cards in hand. 5 mana to cast and 5 to recur seems to be a lot, but it's good enough to include. The only other downside is the potential to kill yourself with the Phoenix's effect, given all the spells that also damage you (Flamebreak, Earthquake, Rain of Embers), combined with whatever your opponent get's through. Overall, it's a solid card.
Fireblast - pretty much an auto-include.
Hostility - I don't dislike this guy. 6/6 with haste for 6 mana is a good deal, and can put game winning pressure on your opponent from out of nowhere, forcing them to make bad blocking decisions. However, when the expansion cards come, I can see myself replacing this for a second Inferno Titan.
Inferno Titan - Do I need to explain why this is good?
Card that were excluded:
Dragon Hatchling/Pyre Charger/Fiery Hellhound/Furnace Whelp - I really dislike the low mana firebreathers. On turn 2, Pyre Charger is basically a 2 mana Raging Goblin. After turn 2, these guys just beg for you to sink mana into them, and it's very risky to do so. After you pump them, your opponent can just destroy or bounce them, costing you huge tempo advantage. There is a potential here to pump mana into these things and trade them for bigger creatures, but that's not enough of a reason to include them. They just tie up your mana and lose you tempo really easily.
Swiftfoot boots - great card, but given the low creature count and the fact that there's no card draw, this card is essential a non-burn, non-threatening creature, and thus, it got cut.
Flames of the Bloodhand - Only hits players, and the secondary effect will only be useful against a few decks. Still, not worth the effort and card cost. I'd rather be burning creatures with Searing Blaze than to use this. A little lifegain doesn't bother me, as Fire Servant and Inferno Titan can quickly take those things away later on.
Firewing Phoenix - Even if it did have the correct 2 toughness, I doubt I'd include it. It's competing with Obsidian Fireheart, and the recurrsion cost is another mana sinkhole. It doesn't feel as immediate of a threat as the Fireheart.
Chandra's Fury - I didn't cut this card until I unlocked over half the deck. It's not that bad, and provides a one-sided sweep to 1 toughness creatures. Although, if you have the deck fully unlocked, you have tons of ways to sweep those creatures before turn 5. In the end, there's just better cards to use at 5 mana.
Skarrgan Firebird - At its best, it's a 6 mana 6/6 with Flying, and that will probably require another mana investment, making this a somewhat unrealiable turn 6 play. I'll take the more reliable Hostility than this. At least that is always going to be a 6/6 when I play it, and the haste is better than the flying here. This is a red deck after all.
Beacon of Destruction - Instant speed and 5 mana for 5 damage makes it worth including.
Flame Wave - I could see using it if you were running the Ruby Medallions. Without the Medallions, no.
Ruby Medallion - I have a lot of reasons for not including this card, and it's probably my most controversial cut. I can see the appeal to this card, acceleration in a red deck. Easier to whip out multiple burn spells per turn. A potential turn 4-5 Titan. However, here's a list of reasons why I didn't include it:
1. Like Swiftfoot boots, it's a non-burn, non-threatening creature (well it isn't a creature). This means it won't immediatly affect the board postion.
2. This deck has no card draw. Given point number 1, that makes this card worse. You spend a card to accelerate, and then run out of gas quicker.
3. The deck's mana curve. I really feel that this mana curve is already great. There's plenty of good cards to play at each mana cost. Not only does this mean there is little incentive to accelerate to a 5 mana card on turn 4, etc, but adding the Medallions is essentially replacing 2 of your burn/threatening creatures with 2 more "land" cards that get cast for mana. And given point number 2, that isn't a good thing with this deck.
4. It does nothing to help with Searing Blaze or Flamebreak, which require 3 red. That's 5 cards in this deck that it doesn't reduce the cost of, which is important to consider if you're looking to utilize the Medallion to play multiple cards per turn.
5. With 24 land in the deck and no card draw, this deck has potential to get mana flooded and run out of gas. The Medallions only help to tap into this potential, and this is not potential that you want to be tapping in to.
Given points 1-5, I feel the Medallions are not worth including in the deck, hence they got cut.