This deck's name may be a little misleading, as this does not contain purely Boros cards. This is because other cards, primarily Balefire Liege, are far too effective in a Modern deck to pass up for the sake of sticking purely to Boros. I feel that the deck's principle, burning while healing, fits the Boros philosophy of justice to the deserving and mercy for the innocent like a glove. So the better this is done, the better i do Boros justice overall.
This deck uses the polar opposites of Burn and Lifegain in a yin-yang relationship, where one does not exist without the other also taking place.
This is less aggressive than other Boros decks, but by no means is it passive.
Using spells like Lightning Helix, Intimidation Bolt and creatures like Blaze Commando and Balefire Liege in unison ensure that every spell you cast does a lot more than your enemy was expecting out of two or three mana.
Deflection Palm and Intimidation Bolt are generally sufficient to deal with anything your burn cannot kill in the short term, but if these fail, Blaze Commando's tokens generally are able to pick up the slack on that front late-game.
While this may seem to be a lot of different things to juggle to a less experienced player, MTG veterans will see the efficiency and effectiveness of the unique play style this deck puts before the player: damage the enemy and bolster yourself at the same time, with a single spell, every time.