Combos:
Combo 1) Tortured Existence + Archfiend of Ifnir. As long as there is a creature in graveyard and a creature in hand, just keep swapping the 2 creatures to activate -1/-1 counters on opponent. Phyrexian Reclamation, Pale Rider of Trostad, Entomb, Buried Alive, or cycling a Archfiend of Ifnir can help set up/restore the hand/graveyard creature ratio making this combo possible
Combo 2) Carnifex Demon + Carnifex Demon can alternate their ability for endless -1/-1 counter spam for 1B each. Baleful Ammit / Soulstinger can be used to refuel Carnifex Demon for more -1/-1 counter spam. In the midst of this combo the Soulstinger will turn it into a -1/-1 counter bomb when it dies that can be used to refuel a depleted and/or solo Carnifex Demon or just give something -5/-5 in counters. The Carnifex Demon strategy is also a good plan B in case the graveyard becomes inaccessible.
Combo 3) Nest of Scarabs / Necroskitter mixed in with these cards really can get kind of crazy.
A few good opening hand strategies:
Dark Ritual and cycle the Archfiend of Ifnir and Reanimate it.
If land is an issue, refuse to play any cards and rely on downsizing to 7 cards each turn to activate -1/-1 counters is an option at this point, I have actually pulled off a victory in this scenario before.
If Reanimate or Animate Dead is in my opening hand, I will often let the opponent go first so that I can draw first and then instead of playing a land I discard Carnifex Demon and then bring it into play turn 2 with Reanimate or Animate Dead
Another strategy is get Sire Of Insanity turn 1 with Dark Ritual + Entomb + Reanimate/Animate Dead. Or Dark Ritual + Pale Rider of Trostad + Reanimate to play it from opening hand... Opponents often scoop after turn 1 Sire Of Insanity
Multiplayer:
This deck also does well in multiplayer games, but it usually results in everyone against me after I wipe the board w/ -1/-1 counters from the Archfiend of Ifnir+Tortured Existence combo and take all their creatures with Necroskitter while everyone has to discard their entire hand because of Sire Of Insanity which results in even more -1/-1 counters from Archfiend of Ifnir and if I have Nest of Scarabs I run out of counters and have to just use a notepad to keep track of my massive army.
EDIT: Kulrath Knight will likely be replacing Midnight Banshee. I just haven't aquired one yet :3
Edit: Revmoved Soulstinger/Midnight Banshee and replaced them with Faith of the Devoted/Kulrath Knight
Edit: Replaced the tags “Mono-Black” / “Aggro” with “Budget” / “Combo,” to better reflect what this deck is.