1. Bad Moon is a good black weenie card, but I don't recommend it because you only have 12 creatures. More creatures would be better, instead.
2. If you want to use Nether Spirit, replace the other creatures with creature substitutes like Chimeric Idol or Sphere or Mishra's Factory, etc.
3. 16 discard spells plus 4 Hypnotic Specter is overkill. If he has something on the board and nothing in hand, what are you going to do?
4. Terror is good, but not if he's playing black. I recommend checking out Contagion or Diabolic Edict. Or better yet, something like Cursed Scroll (or even funny things like Rod of Ruin) since it's more permanent.
5. Specter's Wail is an extremely weak spell. You trade 1 card for one card. So what?
6. Unmask, despite the combo with Nether Spirit, may just run you out of cards here. When going above 8 discard spells, I already consider Bottomless Pit for slots #9-12.
7. With all that discard, I assume you want to play a Rack deck?
8. You need some kind of flexibility or "trick," the simplest being a Kaervek's Spite. You should check out cards that break the mono black mold, like Pox.
Hope this helps.
