I like the fact that someone else is running some Rakdos love. Lord knows it seems to be the forgotten guild from this set because they don't have a shiny new planeswalker and the unleash mechanic seems hard to wield properly.
That aside, I'm liking this as the start of a deck, but not the finished product as I've seen the more outright aggro decks getting bogged down really heavily as of late. The real question is, given your strategy, will you consistently finish off your opponent before turn five? If not, you're going to have to adjust the plan as the prevalence of Thragtusk simply makes the strategy fail (nevermind someone running 4x Centaur Healer).
So, having said that much, what do you do when they start dropping their bombs?
I see Murder which is definitely an underrated removal, but that only deals with four creatures. Personally, I'm a fan of Annihilating Fire over Searing Spear - I see the advantages of being one cheaper, but man, with undying, scavenge, and the herd of Gravecrawlers out there, getting rid of something for good always seems like the better option.
Your creatures need to have a few big ones for your side. Once you run out of Murders you're relying on multiple burn spells or even copying them to drop anything with a toughness higher than four. Without anything bigger than a 2/3 by default (Cryptborn Horror can be big, but only under the proper conditions), you're really going to want some added punches to get those last few life as I can easily see you getting them down to 6-8, maybe even a few lower, and then you're just sitting there mostly screwed (trust me, I did it for an entire tourney with a Rakdos build, it's no fun). Then again, Desecration Demon fits this bill nicely, as he provides a big flyer at only four cost, and even in a worst case scenario provides you with removal of their creatures.
If your creatures aren't really big enough, what's the win con? Copying burn spells? If that's the plan, the Blistercoil Weird - Dual Casting combo would be more effective, as you can essentially triple cast spells.
Lastly, and here's the clincher for most low-end cost decks like this. What happens when you're top-decked? You're going to be drawing 2/1 creatures while they're drawing Resto Angels and larger items. Sign in Blood is a necessity here.
So having said all that, personally, I would:
-2 Reverberate
-3 Cryptborn Horror
-1 Chandra, the Firebrand
-1 Liliana of the Dark Realms
+3 Desecration Demon
+4 Sign in Blood
If your creatures still aren't getting the job done, or if you really like Cryptborn's trample, Bloodfray Giant guarantees a 5/4 trample for only one more.
Anyway, that's some food for thought... good luck with it.