Love the idea of using Generator Servant into Master of Cruelities. I would recommend Whip of Erebos to help bring your guys back in for some more damage and attacking and maybe sideboarding in some Skullcrack

Both good ideas! I may put them in the sideboard, whips especially if I need more sustain. I tried whips mainboard and that just seemed to slow down the pace.

could you post a sort of brief sideboarding guide to this? I'm really considering moving my shitty B/R deck to this since it isn't that expensive a shift and I'd really be interested in what types of decks merit certain shifts

Of course! Obviously every side board is going to be different based on personal preference but I can explain the different cards in mine:

Bile Blight /Doom Blade - Standard removal. Bile Blight is used for aggro decks that use a lot of the same creature whereas Doom Blade is spot removal for some of those bigger threats.

Mogis, God of Slaughter - I used to mainboard 3 Mogis before I added Desecration Demon but it's nice to have that third one in case I'm going up against a control deck. Mogis is nice because he is hard to remove once on the field and slowly eats away at the opponents life or forces them to sacrifice some of their creatures.

Rakdos's Return - Again, used against control mostly. It's nice to have hand advantage or to make them pitch much needed cards after a Duress .

Sire Of Insanity - this is a brand new addition to the sideboard that works extremely well against control. Since this is more of a fast paced deck, you really don't need to worry about losing cards as you can sit comfortably and top deck with a mogis and sire on board. Plus, its an easy turn 4 drop with Generator Servant .

Slaughter Games - Black/Red version of Deicide . This card has helped get me out of some tough situations by being able to remove an opponents win con. Again, because of the double colorless, you can play it a turn early with Generator Servant .

Stormbreath Dragon - this card doesn't really need an explanation as it is so good. Would be mainboarding it if I had room (and definitely will when RTR rotates out). I like to side this in if I need extra flying creatures or if going against white. Once again, being a 5 drop, can be played on turn 3 with haste.

As per the previous comments in this thread, I have also played with the idea of adding Whip of Erebos to the sideboard for that extra sustainability or to bring back Master of Cruelties for a turn (because that's all he's really good for, once he's done his job he just becomes a blocker)