Your deck's mana base is already good so all you need to do I refine your other spells. Black Cat , Cruel Sadist , and Slaughterhorn should go and be replaced by more Reaper of the Wilds . Hero's Downfall is also a great card for any black deck and would work in yours as well.

I appreciate the help! I was definitely planning on getting some hero's downfalls but do you think I should replace my doom blades with them or have both (and sideboard out doom blades when I face a black deck)

I would cut the Enlarge , Giant Growth , and Trollhide for Hero's Downfall

Ok sounds good I'll update once I pick up the cards. Although, enlarge may be expensive but it does come in handy pretty often

If you want this to be a standard deck I wouldn't recommend any one ofs!

Ok, I'm a bit short on cash atm but I'll work on it.Also, are lotleth troll and dreg mangler worth purchasing and adding to my deck?

Run at least 2 of everything!

Planning on removing some of the singles for some more creatures like Dreg Mangler, Varolz, Jarad, Corpsejack Menace, Scavenging Ooze, Courser of Kruphix etc.. Also going to get some golgari charms and such.