This started out as an aggressive boros deck, but after a few overhauls and the addition of blue, I think I've finally settled on something I like.
The goal with this deck is to play defense and control in the early game, until you can land a Purphoros, God of the Forge, then beat down the opponent with Assemble the Legion, Elspeth, Sun's Champion and Stormbreath Dragon. It's also possible, albeit difficult, to gain infinite life with Boros Reckoner, Azorius Charm and Boros Charm. It hasn't really been tested in its current form, and I'm still working on getting all the cards, but it seems like it can do pretty well, and I'm excited to try it out! Here's a little more in-depth reasoning for why I chose each card:
Anger of the Gods - super efficient boardwipe against aggro decks, all of my creatures dodge it except for tokens (which don't matter) and Boros Reckoner (but I still benefit from him getting dealt damage)
Assemble the Legion - absolutely wrecks with Purphoros, God of the Forge on the board, and it's still a solid card without him.
Azorius Charm - utility, disruption, infinite combo potential, this card is just great.
Boros Charm - see Azorius Charm
Boros Reckoner - great defensive creature, totally ruins all your opponents plans for combat. It also gives tons of devotion for Purphoros, and enables the infinite combo.
Chained to the Rocks - super efficient creature removal, and I'll almost always have a mountain to chain them to
Chandra, Pyromaster - revives Chandra's Phoenix if I side it in, removes small creatures and blockers, and generates card advantage
Detention Sphere - kills enemy planeswalkers and other problem cards
Elspeth, Sun's Champion - 6 damage per turn with Purphoros? I think so. Even without him, this card usually ends games.
Frostburn Weird - one of the best defensive creatures, dodges Anger of the Gods, gives devotion for Purphoros and Master of Waves, and can hit for 4 damage if I want him to
Magma Jet - kills small creatures, and scry is nice
nykthos-shrine-to-nix - can be used for red, white or blue mana (usually red) since I have lots of devotion to all 3 colours. Also, if I set it up right, I can use it for a massive Sphinx's Revelation
Purphoros, God of the Forge - the main force behind this deck, it should be pretty obvious why he's in here
Sphinx's Revelation - I just like having one of these, in case I'm stuck in the late game with no cards and nothing to do
Stormbreath Dragon - get in those beats! 4 damage off the bat, 6 if I have Purphoros, and the possibility to go monstrous later, this guy is awesome.
Sideboard:
Chandra's Phoenix - to replace Anger of the Gods against control decks.
Essence Scatter - for those creature-heavy decks where Azorius Charm and Magma Jet isn't enough
Glare of Heresy - for enemy Detention Spheres and Elspeth, Sun's Champion
Mizzium Mortars - more big creature removal
Pithing Needle - for use against AEtherling or planeswalkers
Supreme Verdict - for the aggro decks
Turn / Burn - to kill opposing gods and Master of Waves
since it was a dead card 80% of the time