And why u no Rakdos Charm

Frank lepore actually did a modern Monday recently that reminded me of your deck!

http://magic.tcgplayer.com/db/article.asp?ID=12240 (if you don't want to click the link, just search up frank lepore and find his tcgplayer articles, look for "modern Monday - dregdevine")

Check it out, it has a lot of cool stuff you might wanna consider, like Lotleth Troll, Gravecrawler, Vengevine, and Faithless Looting, to name a few.

If you like the bloodrush mechanic as a good way to fill your graveyard and boost creatures, you should look into getting your hands on some Pyrewild Shaman's. They have decent boosting and can be used throughout the game as an aggro recursion. because of the high amount of creatures with the sub-type 'Zombie', you could easily run either Gravecrawler or Relentless Dead. You also have a high enough amount of removal that you could easily remove one or two for a Vraska the Unseen or a couple Deathrite Shaman's.

Mainboard Thundermaw Hellkite (or any other creature above 5 CMC, really) with no ramp or creature cheat whatsoever in modern - Most of the time it'd be pretty much a dead card for you. Would suggest instead:

1) Faithless Looting. Good for refilling and dumping creatures in the 'yard.

2) Vexing Devil. Always, always a good play.

3) Vengevine. If you utilize the grave, that's the guy for ya.

Also, sideboardwise - too. many. removal.

Now seriously, you have too many removals in the sideboard. You might wanna consider in replacement to some:

Ancient Grudge, Relic of Progenitus, Atarka's Command, Fulminator Mage, Kolaghan's Command, Nature's Claim, Ratchet Bomb, Damnation, Leyline of the Void, Surgical Extraction.

Best of luck!