On another note, I finally scrounged up the courage to post a decklist. It's a tweaked list off of this board. My thanks go to the original poster.
WARNING!!! This got really long! Don't feel bad about not reading everything. Just check out the decklist and go from there. You won't hurt my feelings. Promise.
With that being said: here goes nothing.
It's a combo deck, which goes wide and then tries to win with anthem effects. I dropped part of the original thopter package for more Allies synergies and I have been fairly successful with the deck. For the list I tried to concentrate on maxing synergies to minimize bad opening hands/topdecks. I didn't keep track, but I'm roughly 20/5 with it.
The deck can have aggressive starts, t5 kills are possible, but this is not necessarily the game plan. It is rather to develop your board for the big turn, when you rush your opponent with a wide board of possibly pumped weenies.
I try to play the deck for maximum indirect card advantage, when possible. This means, I'm often holding spells or lands, even though I could play them. Don't get me wrong: I always try to improve my board, but I'm not aggressively pushing for the win, as I'm trying to avoid emptying my hand too quickly.
Creatures
1x
Kytheon3x
Akoum Stonewaker2x
Perilous Myr 2x
Abbot of Keral Keep 2x
Knight of the White Orchid3x
Thopter Engineer 3x
Firemantle Mage 2x
Lantern Scout 2x
Pia and Kiran Nalaar Non-creature spells
4x
Dragon Fodder 1x
Kytheon Tactics 1x
Exquisite Firecraft 3x
Retreat to Emeria3x
Valor in Akros 2x
Unified Front 1x
Gideon, Ally of ZendikarLands
2x
Mortuary Mire 3x
Foundry of the Consuls 4x
Evolving Wilds2x
Clifftop Retreat 5x
Plains 6x
Mountain 1x
Forest 1x
Canopy Vista1x
Prairie StreamCard by card analysis:
Kytheon is always good: Played on T1 and followed by Dragon Fodder or Stonewaker, he is easily flipped on T3. Late he is a decent blocker and also easily flipped, unless you've just been wiped. When flipped he can goad your opponent's best creature into attacking him to get you into a better attacking position, protect one of your creatures for a turn, or beat down for 4. Don't forget to turn him into a creature, before you use anthem effects.
Stonewaker can provide early mana-efficient aggression against an empty board and triggers valor late game. Attacking for 5 with it on turns 3-5 is tempting, as it puts pressure on the opponent and creates indirect card advantage. This will keep you from developing your board, though. I'm considering cutting one, as I don't like drawing more than one in my opening hand.
Perilous Myr occupies two of my four switch-spots. I'm giving it a shot for it's synergies with Engineer and Pia & Kiran.
Abbot's etb becomes better the latter she is played, as the deck goes up to 4cmc, and her prowess will only ever trigger on your turn in this deck. Still, she is very efficient. She is one of the few card advantage cards you have, may trigger landfall, and should still be played on T2, if there's no alternative play. I tried cutting her for more synergistic cards and missed her right away. So, back she is.
Knight of the White Orchid's WW cmc and his very conditional trigger often leave him an over-costed 2/2 first-striker. But when he triggers, he becomes Mr. Synergistic! He ramps an untapped land, thins the deck, triggers landfall for Stonewaker and Retreat, and fetches blue or green mana for Unified Front. Being on the draw and/or playing against ramp helps triggering him in the early game, as does cracking a Foundry late.
Thopter Engineer is a two-for-one that speeds up your artifact creatures, adds a 1/1 flyer to the board and is a decent blocker. Played on curve after Kytheon and another creature her thopter, too, can help flip Kytheon on t3. She also sets up Pia & Kiran nicely.
Firemantle Mage is mass evasion on a stick, which makes him stronger late. But since Lantern Scout, Retreat, Gideon and Unified Front can trigger him again, playing him early is fine.
Lantern Scout is in the deck, cause it buys you time. I finished several games with 30+ life, because of it. It's power of 3 also makes a difference and it's an Ally.
Pia & Kiran is one of your best board builders. It's a three-for-one with burn that is best with Thopter Engineer and/or Valor in play.
Dragon Fodder is the most efficient token producer in Boros to build/rebuild your board. It's also great with Valor.
Kytheon's Tactics I am not sure about. It doesn't build the board, but I'm giving it a try to find out, whether it may be a good topdeck late.
Exquisite Firecraft is the most efficient burn spell in the pool; no doubt about it. As a finisher it feels win-more, though, but it's nice to finish off a big blocker after, or a small one before combat.
Retreat to Emeria is the most versatile card in the deck and is best played when you can activate it in the same turn, which is why it is a terrible topdeck. So, leaving an uncracked Evolving Wilds in play can be a good idea, when you're topdecking. Cracking Evolving Wilds with Retreat in play is also one of the few chances you have at using a combat trick. Choosing between Retreat's two abilities can be tricky at times, especially when you have several in play. Trying to produce pumped surprise blockers against an opponent's attack has taught me some painful lessons about the stack ??!!! Also, don't forget that it produces Allies which may retrigger Firemantle Mage/Lantern Scout. With Valor in play all you ever want is tokens, though.
Valor in Akros is a card receiving lots of hate on this board, and for good reason. Without the right deck it truly means a wasted t4 and is definitely win-more. It being a maximum three-of in a format without enchantment tutoring doesn't help its reputation either. Enter Retreat. Suddenly you can play six cards which produce temporary anthem effects with the same cmc, which even combo, when you have both in play. With seventeen cards that can put up to four creatures into play at once, plus three Retreats, Valor becomes worthwhile. Now, playing it on t4 means board development. This deck is no Valor build-around. It's a deck that can make good use of it. And my inner Timmy loves it! Similar to Retreat and Wilds, having an uncracked Foundry of the Consuls in play may turn a terrible topdeck into a possible finisher.
Unified Front is responsible for my funky mana base. It provides lots of uses: simply casting it with no synergies will develop your board, with Allies in play it triggers them, and with Valor it is often GG. Obviously, you should always try to cast it for 3+ tokens, but sometimes all you need is the Allies trigger.
Gideon is another perfect fit for this deck. He can put 2/2 Allies into play to build your board, triggering any Allies you already have. He can provide a permanent anthem, or become the biggest creature your deck has to offer. His Loyalty is very useful, which is why I usually +1 him right after I cast him. This will give me the chance to use his -4 on my next turn and still keep him. Try not to cast him with a flipped Kytheon on the board, as this will force you to choose between the two of them.
Mortuary Mire: I'm a fan of this card, and it has won me many a game with lots of different decks. It's black mana is never relevant to me. I only ever want it for its etb. In this deck it creates card advantage against an opponent's removal and helps rebuilding after a sweeper. The fact that this deck can actually make good use of Mire's colored mana to cast a bigger Unified Front is just gravy.
Foundry of the Consuls is a natural fit with Engineer, Pia & Kiran and Valor. Nuff said.
Evolving Wilds is probably the best example for how different cards can and should be played depending on what phase of the game you're in: during the first two turns these should be used for mana fixing, but starting on turn three you can already consider them possible landfall combo pieces, and may keep them to set up a big turn.
The singletons of Forest, Canopy Vista and Prairie Stream are meant to be fetched with Evolving Wilds and Knight of the White Orchid respectively. They are in the deck to enable Unified Front.
Mountains, Plains and Clifftop Retreats? It's a Boros deck, duh!
Wow, this got a lot longer than I had anticipated! Thanks for reading and your feedback is always welcome.
P.S.: Should my English sound somewhat off (preposterous, patronizing, or just plain weird), I’m sorry: it's not my native language and I haven't been writing English for quite a while.