Boros Charm to save Spark Trooper from being easily killed, as well as protect from wipes. Also can help get in the last damage you need, or make Vampire Nighthawk more evil

I would suggest cutting Spark Trooper and Vampire Nighthawk for a 4th Gravecrawler and a playset of Diregraf Ghoul s, your 3 drop slot is already overfilled and your land count already forces the deck into holding a more aggressive attitude, so you'll be better off with more 1 drops.

The Increasing Ambition isn't a spell you'll likely ever want to cast in an actual game unless it's your last card or you really need to kill an opposing planeswalker so overall its too slow. The Lingering Souls s probably could be something else as well. Boros Charm would do nicely in those 4 slots, it can hit for a good chunk of damage, can save your team, and it can make you distantly possible to create the combo with Boros Reckoner .

For some sideboard suggestions I'd suggest not going with Rest in Peace for your graveyard hate spell as it neuters your deck likely more than your opponent's (from a quick glance it would shut down most of the functionality of 13 of the deck's current spells, Blood Artist and undying triggers wouldn't happen, there'd be no flashback or Gravecrawler s coming back, etc.). You might be best off with running something like Cremate or card:Tormod's Crypt.

You could really use some extra removal (at least for the sideboard), Oblivion Ring might work best as a catch all.

B/R has some of the best spells to fight control decks and midrange decks in card:Rakdos's Return and Slaughter Games , I'd highly suggest adding these somewhere into your sideboard as well.

Really useful comments, Demarge!

I'll update the main and sideboards, but i'll keep Spark Trooper , he's very powerful and give me some extra turns in a rush.