"You were defeated the moment you declared your aggression." - Gideon Jura
This deck is completely built around forcing your opponent to attack you, and making them suffer for it.
Sleeper Agent gives my opponent a 3/3 creature that Shocks them every upkeep. This can be especially useful if my opponent is using a deck with little to no creatures, as this gives me something to bounce damage back from.
Wall of Essence and Souls of the Faultless provide fantastic ground defense, as they each gain me life proportional to the damage they take. Souls of the Faultless takes this a step further, and also burns my opponent when he blocks. Their 0/4 bodies also work perfectly alongside Sleeper Agent, who can't get through their big butts to attack me, and so will just sit there and Shock my opponent every turn for free!
Hunted Lammasu: At first, this seems like a weird choice to put in here. However, he actually fits with the theme quite well; being a 5/5 flyer for four mana is very strong, and while giving my opponent 4/4 token may seem like a downside in any other deck, it's actually a bonus here. Giving them a 4/4 means that's another 4 damage I can reflect back to their face whenever I want to! And swinging in for 5 in the air is nice too.
Harm's Way, Deflecting Palm and Boros Fury-Shield reflect back damage to my opponent's face, using their own power against them.
Skin Invasion and Lust for War both force attacks from opposing creatures. Skin Invasion is very cheap to cast and becomes a 3/4 when its host bites the dust, and Lust for War bolts my opponent every turn.
Lightning Bolt and Lightning Helix provide basic burn damage and occasional spot removal if need be.
THE SIDEBOARD
Curse of the Nightly Hunt: For when my opponent refuses to run into my walls willingly.
Batwing Brume: While this deck excels at dealing with individual, decent-sized creatures, it has issues with swarms of little ones. This hoses those decks HARD.
Boros Charm: Makes my walls indestructible or deals 4 damage to my opponent's face. Useful for when I need to go all-out burn.
Hallow: A great tool to go up against burn decks.
Intervention Pact: A nice tool against any extremely aggressive builds in which my life matters more then their death.
