Looks good. I would add in Ogre Slumlord to add some more tokens to sac. Then you aren't having to get rid of other demons
Love too see Seizan, Perverter of Truth in this list.
What seems the best to replace Kuro for? He's a damn expensive demon... but removal on a stick is amazing. Especially -1/-1
Nykthos, Shrine to Nyx
Wayfarer's Bauble + Burnished Hart are insane with Cabal Coffers and friends
Gray Merchant of Asphodel is such value in mono B, looks like a dork but is a win con on its own
You really need some haste. Probably Lightning Greaves + Swiftfoot Boots
If budget isn't an issue, a little known mono B tech for the best ramp is running all the swamp fetchlands, ALL of them, and combining it with Rings of Brighthearth and Crucible of Worlds. Not only the best non-green ramp in EDH, but also breaks Cabal Coffers in half. Pricey as fuck though
Cut:Demonic Taskmaster, Increasing Ambition, Diabolic Revelations, possibly Halo Hunter, possibly Magus of the Coffers
The flavor is strong in this one.
I'd probably cut Helldozer, Strip Mine / Wasteland / Dust Bowl are easy to add in Mono-B.
I don't think new Lilly is that great. She won't be ulting, her removal is crummy and kills her, and fetching a basic swamp isn't amazing.
Contamination could be super evil here. There's another enchantment that has a similar effect from ice age, forgot the name though, also evil.
Decree of Pain best board wipe. Read the Bones, Sign In Blood, Ancient Craving, Ambition's Cost more card draw options if you want them. You have very few ways to interact with artifacts/enchantments, probably want a O-Stone or that new M15 one, or Karn or Gate to Phyrexia.