My guiding philosophy in creating new options for Dungeons and Dragons -- spells, prestige classes, magic items, the rest -- is that new rules should be like existing core rules This is not just some wacky idea of mine: check out these passages from the PHB and DMG:
PHB, page 110:
If you want a fighter who used to work for the thieves' guild as an enforcer but who is now trying to become a legitimate bodyguard, he could be proficient only with the weapons and armor available to rogues, have 4 skill points per level instead of 2, and access to Bluff and Sense Motive as class skills.
DMG, page 174:
When modifying a class, always take the following steps: 1. Look to see which standard class seems to be most like the end result that you want to create. 2. Look to see if another class has special abilities that can be swapped for something this class has in order to create what you want. 3. Look to all the other classes and match the newly modified class against each one, taking into account the following factors: Hit Dice, BAB, Save Progression, Skill Points, Skill List, Weapons and Armor, Spells, Special Class Features.
Take something away, put an equivalent something in. Trade-offs. This kind of power and feature balancing applies equally to PrC design. That said, let's look at fighter-oriented prestige classes.
Fighters already have a LOT of flexibility because they have so many feats. If you did not want to create a Crossbowman PrC, you could still easily make one as a fighter by taking many crossbow-oriented feats to accomplish the same thing.
But some combat options are not as easily replicated with feats. If you have a theme that can't be built with the existing feat structure, then a new PrC may do the trick. From the DMG, as models, consuder the Duelist, the Dwarven Defender, and the Horizon Walker. To a lesser degree, the Arcane Archer is also relevant.
All three get a fighter's BAB, which is what makes them fighter-oriented, of course.
The Duelist gets one good save (Reflex) and 4 base skill ranks per level. The Horizon Walker gets one good save (Fortitude) and four skill ranks too. The Dwarven Defender has two good saves (Will and Fortitude) and just two skill ranks per level. That's a good model to follow: Four ranks and one good save, or two ranks and two good saves.
The only thing left to talk about is class abilities. The natural inclination to add combat abilities must be resisted ... especially combat abilities that stack. Instead, consider adding non-combat and semi-combat powers that really fit the theme of the PrC. And consider adding new combat options that increase flexibility and offer new ways to attack, as well as some defensive powers.
Before we look at some specific examples of making things balanced, let's consider class abilities. There are two kinds: those that improve, and those that do not.
Let's take the Dwarven Defender. He really has only five class abilities: Defensive Stance (improves), Uncanny Dodge (improves), Trap Sense (improves), Damage Reduction (improves), Mobile Defense (does not improve). Note that EACH and EVERY improvement is noted on the prestige class table!
Let's take the Duelist. Improved Reaction and Precise Strike both increase and are noted on the table. Canny Defense increases but is NOT noted on the table! An exception! The others do not improve.
And the Horizon Walker: None improve.
Now look at what these class abilities actually DO.
The Horizon Walker is easy. Each ability gives a +1 to hit and damage vs. a creature type, AND gives a non-combat bonus. This makes the Horizon Walker feature rich but certainly not overpowered.
The Duelist has unique abilites:
- Canny Defense -- Helps AC if you wear no armor -- Defensive
- Improved Reaction -- Bonus to Initiative -- Offensive, but does not help attack rolls or damage.
- Enhanced Mobility -- Better AC vs some AoOs -- Defensive
- Grace -- Helps Reflex Saves -- Defensive
- Precise Strike -- Extra damage dice -- Offensive
- Acrobatic Charge -- Boosts mobility -- Offensive, but does not help attack rolls or damage
- Elaborate Parry -- Boosts fighting defensively -- Defensive
- Deflect Arrows -- Defensive
Note that only one Duelist ability boosts damage, and that since the PrC basically requires no armor or shield, all the Defensive abilities compensate for lack of armor.
Now look at the Dwarven Defender:
- Defensive Stance -- Offensive and Defensive
- Uncanny Dodge -- Defensive
- Trap Sense -- Defensive
- Damage Reduction -- Defensive
- Mobile Defense -- Movement
Once again, the bulk of the PrC's abilities are defensive. And the one offensive ability has limited uses per day.
It is also helpful to look briefly at the Arcane Archer, since ALL the PrC's abilities are offensive. Of the six abilities, one improves (Enhance Arrow), and each improvement is the only thing gained that level. Another (Imbue Arrow) extends the range of spells, but the PrC does not otherwise improve spell casting. The other four are all once per day only.
So let's make some generalizations. In general, a Fighter-Oriented PrC shouldn't be overloaded with Offensive abilities. Those offensive abilites that the PrC does have might be limited by uses per day, and/or in some other way (no movement, no use of armor, etc). And do not neglect the use of non-combat abilities that fit the theme of the PrC.
To close, let's look at one more passage from the DMG, on new spell creation, from page 35.
If a spell is so good that you can't imagine a caster not wanting it all the time, it's either too powerful or too low in level.
The same applies to prestige classes. If almost every fighter would rather take the PrC than continue in fighter, then the PrC is either too powerful or the entry requirements are too low. If you look at how existing PrCs do it, and follow their example, your new PrC will not be too potent.
Next time: Putting my money where my mouth is, I offer a new fighter-oriented PrC.