First: What it doesn't have yet (to get that out of the way)
But now for the fun stuff. What does this blackguard have?
As always, I'm happy for suggestions, feedback, everything.
Are the abilities too strong? Too weak?
I think the Power over X penalties might be too much, but have to come up with a different formula yet.
Does the Sneak Attack or whatever only work against the target of a Smite Good? How much sneak attack do they get? 1d6 every 3 levels?
I think the Power Overs are kind of weak, since they're situational. Also, just to keep the book-keeping easier, you might want to make the Power Over Weakness remove 5 points of DR per hit (1 point if the DR is X/-).
It might make sense to come up with new Powers Over that affect different things, like a penalty against All Saving Throws (or at least all Will Saves), a penalty to Spell Resistance, maybe (MAYBE) a penalty to Armor, Shield, and/or Natural Armor?
Are the Afflictions (which are really cool!) going to be actual conditions, like Shaken, Fatigued, etc.? That would be really neat. My only points of contention are Diseased and Poisoned, because there are so many different diseases and poisons. Are you going to treat it like the Cause Disease and Poison spells? Or just have Cause Disease and Poison on its spell list?
EDIT:
Unholy Champion should do 2 points of Strength or Dexterity damage. That way, there are fewer dice to roll, so combat goes quicker, and the opponent always takes some kind of penalty.
Does the Sneak Attack or whatever only work against the target of a Smite Good? How much sneak attack do they get? 1d6 every 3 levels?
No sneak attack. Instead, they get double smite damage against "stabbable" enemies, the way paladins get double smite damage against evil dragons, outsiders and undead.
I did it this way because I felt smite was already a very powerful attack option but the sneaky stuff should stay in nonetheless, and before I copy this thing to anti-smite-good and think about what you could do instead of undead, I came up with this.
I think the Power Overs are kind of weak, since they're situational.
Actually, I was worried they might be too much. If the party does work together (or the blackguard has the right henchmen), the penalties can be brutal. Be hit a round or two by a blackguard and stuff like fear spells or hold person/monster looks quite nasty.
Also, just to keep the book-keeping easier, you might want to make the Power Over Weakness remove 5 points of DR per hit (1 point if the DR is X/-).
Hm... I guess that might not be out of line.
It might make sense to come up with new Powers Over that affect different things, like a penalty against All Saving Throws (or at least all Will Saves), a penalty to Spell Resistance, maybe (MAYBE) a penalty to Armor, Shield, and/or Natural Armor?
All saves: could get pretty nasty pretty quickly, all will saves might be okay, but I'm not too sure. But it's not that much of a step beyond weakness to enchantment, so this could be okay.
Spell resistance: Sounds good. Won't make things too easy, might actually be better than hexing saves.
AC: I'm not sure, this could get extra nasty extra quick. The ability would practically snowball, and even worse than the DR thing.
Are the Afflictions (which are really cool!) going to be actual conditions, like Shaken, Fatigued, etc.? That would be really neat.
Yes, they are - they more or less do mirror Mercy. They're already in the PDF, like everything else (THE VERY FIRST LINE IN THE FIRST POST IS A LINK - I GUESS I SHOULD HAVE POINTED IT OUT MORE)
My only points of contention are Diseased and Poisoned, because there are so many different diseases and poisons. Are you going to treat it like the Cause Disease and Poison spells? Or just have Cause Disease and Poison on its spell list?
Well, the basic version works like "anti-mercy": You inflict a single standard condition. For diseased, cursed and poisoned it emulates contagion, bestow curse and poison, respectively.
The nasty part comes when the blackguard is under some negative condition. If he is, and has chosen those conditions as an affliction (something I might have to rename to avoid confusion with the general set of status called affliction, from the PFRPG glossary), he can cause one standard affliction from his list PLUS all the conditions he currently has and has as affliction. If the victim fails its saves, it gains all the afflictions the blackguard has (at the exact same strength the paladin had them - durations, effects, DCs etc) and the blackguard is cured.
Unholy Champion should do 2 points of Strength or Dexterity damage. That way, there are fewer dice to roll, so combat goes quicker, and the opponent always takes some kind of penalty.
Not a bad idea. this is going into the final version.