Purple Dragon Knight
Shadowdancer: Love the name. This is supposed to be a Rogue-type class, but its abilities are somewhat redundant with those of a Rogue. In fact, the Shadowdancer’s best unique ability, Hide in Plain Sight, is acquired at level 1. This enables it to use the Hide skill even when within sight of enemies and even in the middle of combat, making it deadly in combination with Rogue skills. In order to become a Shadowdancer, a character must have the Dodge and Mobility Feats, as well as 10 points in Hide, eight in Move Silently and five in Tumble. Shadowdancers can use simple weapons and light armour. They have a d8 HP progression base and get three points of BAB every four levels. They gain six Skill points per level, plus any extras from Intelligence bonuses, and bonus Feats every three levels starting from level 13. Their primary Saving Throw is Reflex. The Shadowdancer learns Uncanny Dodge at level 2, then improved versions at level 5 and 10. It also learns Shadow Evade, which grants it a 5% concealment bonus (meaning that incoming attacks have a 5% chance to miss), a one-point AC bonus and a five-point damage reduction from normal weapons three times per day. This steadily improves to reach a maximum of 20% concealment bonus, four-point AC bonus and 18-point damage reduction from weapons below +5 enchantment at level 30. Starting from level 3, the Shadowdancer can also summon a shadow creature to help in combat, with two upgrades at level 6 and 9. Dexterity is clearly the primary attribute here, making elves and halflings a good pick in terms of race.
Blackguard: This is the first time that BW specifically caters to players that prefer Evil protagonists, despite the fact that there are no Evil henchmen on offer. The Blackguard is the opposite of a Paladin (right down to the class symbol), similar to the Dark Knight class from JRPGs: a champion of an Evil deity. In order to become a Blackguard, a character must be Evil (duh), have six points of BAB, five points in Hide (a Class Skill for Rogues, Bards, Monks and Rangers) and the Cleave Feat, which requires at least 13 Strength or one level as a Monk. Blackguards can use simple and martial weapons, as well as shields and heavy armour. They have a d10 HP progression base and get one point of BAB per level. They gain two Skill points per level, plus any extras from Intelligence bonuses, and bonus Feats every three levels starting from level 13. Their primary Saving Throw is Fortitude. They can also add their Charisma bonus to their Saving Throws and have an ability called Smite Good, which deals more damage to Good creatures (but how many of those will you actually encounter?), depending on the Blackguard’s Charisma. The only real difference with Paladins is that they don’t have immunity to disease or fear, or any Clerical spells. Instead, they can summon various Evil creatures, such as ghasts or succubi (none are particularly potent, alas), which they acquire every two levels between level 3 and 9. They also gain a smattering of offensive spells and one spell that boosts their Strength (which stacks with the eponymous Arcane spell), as well as the ability to perform Sneak Attacks at level 4, with improved damage every three levels after that. Strength and Charisma are the key attributes, so while half-orcs would be perfect for the former, the latter disqualifies them. The same goes for dwarves. This leaves humans and half-elves as good candidates.
Assassin: Another riff on the Rogue, but this time with a distinctly Evil twist. As the name implies, Assassins are all about dealing death as swiftly and efficiently as possible. In order to become one, a character only needs eight points in Hide and eight in Move Silently, aside from being Evil, of course. Assassins can use simple weapons and light armour. They have a d6 HP progression base and get three points of BAB every four levels. They gain four Skill points per level, plus any extras from Intelligence bonuses, and bonus Feats every four levels starting from level 14. Their primary Saving Throw is Reflex. An Assassin’s bread-and-butter is the Death Attack. It works just like a Rogue’s Sneak Attack, except that, in addition to extra damage, it also has a chance of paralyzing the target. The extra damage starts at 1d6, then improves by 1d6 every two levels. What’s more, this stacks with the bonus from Sneak Attack, so Rogues multiclassing into Assassins have a clear advantage. At level 2, Assassins also get a one-point bonus to their Saving Throws against poison, with an extra point every two levels, up to a maximum of 15 at level 30. Level 2 also grants them Uncanny Dodge, with improvements at level 5 and 10. They also gain a smattering of Arcane spells dealing with concealment. Dexterity is clearly the main attribute here, so elves and halflings are probably the best picks in terms of race.
Arcane Archer: The only SoU class to have a racial restriction (HotU adds another): only elves and half-elves need apply. As its name indicates, the Arcane Archer combines archery and Arcane magic. Thus, in order to become one, your character needs to have six points of BAB, the Weapon Focus (Longbow or Shortbow) and Point-Blank Shot Feats, as well as one level as either a Bard, Sorcerer or Wizard. Arcane Archers can use simple and martial weapons, shields, as well as light and medium armour, although the latter will impact their ability to cast. They have a d8 HP progression base and get one point of BAB per level. They gain four Skill points per level, plus any extras from Intelligence bonuses, and bonus Feats every four levels starting from level 14. They’re one of the classes that have two primary Saving Throws: Fortitude and Reflex. At level 1, the Arcane Archer can enchant its arrows, adding a +1 enchantment every two levels for a maximum of +15 at level 29-30. This stacks with any enchantments the arrows or bow may already have. At level 2, the Arcane Archer can use Imbue Arrow three times a day, which makes it explode for 10d6 damage upon contact. The damage increases by one point every two levels starting from level 11, for a maximum of 20d6 damage at level 30. The primary attribute here is Dexterity, but Intelligence also helps, as your character will necessarily have the ability to cast at least a few spells.
Harper Scout: This is a strange class, because, unlike its peers, it only has five levels. The Harper Scout is a sort of hybrid between the Ranger and the Bard, but it’s mostly there to enhance your character’s primary class. In order to become a Harper Scout, a character must be Good or Neutral, have the Alertness and Iron Will Skills, as well as four points in Discipline, four in Search, six in Lore and eight in Persuade. They can use simple weapons and light armour. They have a d6 HP progression base, gain three points of BAB every four levels, and four Skill points per level, plus any extras from Intelligence bonuses. They gain a bonus Feat at level 1 and 5, but there are only two to choose from anyway. Unless you wait until your character is above level 20 before turning them into a Harper Scout, in which case, there will be more bonus Feats to choose from. Harper Scouts are also one of the classes with two primary Saving Throws–Reflex and Will–and gain various ways to improve their Saving Throws beside that. They can use an offensive song (but need Bard Song to make use of it) and have improved identification abilities. They can cast Sleep and Invisibility, as well as spells to improve Dexterity and Charisma (which stack with the eponymous Arcane spells). At level 5, Harper Scouts can also create potions with the same effect…but spend money and EXP to do so. It’s hard to say that the class has a primary attribute, but it can help base classes that rely on Dexterity and/or Charisma, such as Paladin, Bard or Sorcerer. Elves and halflings would be good candidates, as would humans and half-elves. Still, there are plenty of better classes to choose from.
There’s a sixth prestige class available upon installing SoU (or HotU, it doesn’t matter which one), provided you apply patch 1.69.
Purple Dragon Knight: Much like the Harper Scout, this class only has five levels and…isn’t very good. It doesn’t help that there’s a long list of requirements to unlock it. In order to become a PDK, a character can’t be Evil or Chaotic. S/he also needs four points of BAB, the Mounted Combat Feat (which is useless in the OC and its expansions), as well as one point in Persuade, one in Intimidate, two in Ride, two in Listen and two in Spot. PDKs don’t gain any additional abilities in terms of weapons or armour, so whatever your character’s other class(es) allow applies. They have a d10 HP progression base and get one point of BAB per level. They gain two Skill points per level, plus any extras from Intelligence bonuses, but no bonus Feats. Their primary Saving Throw is Fortitude. In terms of abilities, PDKs are clearly designed for a party, which doesn’t make a lot of sense if your character only has one henchman. They gain four abilities that improve party members’ performance: one for a one-point attack and 20% speed bonus, one for a 2d10 HP bonus, one for a four-point evasion bonus, and one for a one-point attack and damage bonus, with a two-point bonus against mind-affecting spells. It’s just that Bard Song combines similar effects under a single ability and, even at its most basic, lasts longer. There’s also one offensive spell and one ability that gives the PDK a two-point bonus to attack, damage, Saving Throws and Skills against a single opponent once per day. Honestly, you’d be better off picking almost anything else. Still, if you must, Strength is the main attribute, and Charisma also comes into play for one of the abilities. This means that humans and half-elves would be good picks.