Zombies and even more zombies. Also, a game-winning mass-reanimation combo at the low low cost of 14 mana.
Basically, hang out and be a zombie kindred deck until you can find Mortality Shift and 14 Mana, then hopefully resolve both Morality Shift and cast Balthor and activate his ability. If all goes well, the game should either end on the spot due to a big Gray Merchant trigger, or the massive swing in board presence should seal the deal if not.
I find myself tutoring for ramp a lot of the time with this deck. Sometimes you'll want to tutor for a board wipe or something, but if you're closing in on having enough mana and you're not under any particular pressure, grab Morality Shift as a way to end the game with your tutors.
A lot of card choices here have multiple black mana symbols to power up Nykthos, so keep that in mind if you build this and make some modifications.
A big Torment of Hailfire is always a good backup if you're getting your graveyard hated out.
You can cast Balthor out without the combo and just use his ability for value. Thanks to the command zone, you can probably do this a few times before it gets too pricy.
If you think you can get him to survive a turn cycle, don't be afraid to cast Balthor out with no intention of activating him on the same turn. This can be risky though, so be cautious!
There aren't any Minions in this deck, sadly. Ignore that part of Balthor's text.
You can play a bit of politics with Scheming Symmetry to get your friend to deal with a more pressing threat while you find some ramp or Morality Shift.
If you want to play this at a lower power table, just take the Morality Shift out and play some other mass-reanimation spell probably.