Hi @frdave - It's been a long time, and I hope all is well with you and yours!

For purposes of XP cost, the Class Builder cares only about the class's spell level maximum - the progression rate (or the level at which new spell levels are available) does not factor. So we can break this down:

The XP Cost for spell level maximum is covered under the Spell Casting ability (pg. 9): 100XP per max. spell level for divine spells and 400XP per max. spell level for arcane spells. The Crusader's maximum is 3rd level divine spells for an XP cost of 300XP. The Bard's maximum is 4th level arcane spells for an XP cost of 1,600XP.

The spell progression rate is entirely up to you, and the tables in the book reveal my OCD bias - I attempted a more "normalized" progression instead of emulating the rates in the rulebook. On the plus side, that means you can change the progression rate to whatever suits your setting best - it has no bearing on the XP costs.

Please let me know if this helps. In the meantime, thanks for your kind words and support!

-Erin

@erin-smale Whew! That makes me feel so much better...no pattern and no math seemed to make sense. That I can just arbitrarily decide makes so much more sense than anything I was trying. BTW the fact that despite having a robust mathematical foundation, the tremendous amount of wiggle room and arbitrariness is what makes BX Options: Class Builder work so well. I will be using this A LOT.

Thanks for the quick response!

P.S. Me and mine are hanging in there and muddling through as we always seem to manage. I pray you and yours are doing well also.

@frdave - You're quite welcome. Spell progression rates are a bit messy, so after struggling with them for a bit, I opted to take an easier approach. 

As a side note (and of possible interest), the image below reflects the spell progression for the classic classes (Cleric, Elf, and Magic-User). 

• Total Spell Levels refers to the sum of all spell levels the class may memorize at each level.
• Progression refers to the number of additional spell levels gained at each experience level.
• New Spell Level shows the experience level at which new spell levels are gained.

The Progression set is probably the most interesting to me, because it shows how uneven the gain is from level to level. It's hard for me to make sense of it from a game design perspective, which is why I ended up removing it from the XP calculation in the Class Builder. It's not so much that I disagree with the numbers (they're fine), but more that I couldn't tell you how to emulate it for new classes. ? 

Love the book so much I went and got the POD version, which I never do.  Two things come to mind that I would like to know.

1.  Are you going to release worksheets for each of the example classes in the book?  I see a few abilities I would like to put into some new classes or variants but would rather have a better idea of the cost to keep things balanced.

2.  I don't remember seeing it, it could be there, but do you have examples of classes that get additional attacks per round after so many levels?

Probably will have more questions but figured this would be a good start.  Thanks for the great book!

@evil-jeff - Happy to hear this book pushed you over the POD edge. ? 

In answer to your questions: 

1. I hadn't planned on releasing separate worksheets, but yours is among a handful of sporadic requests. It will be a couple of weeks before I get to this, but I'll post here when the worksheets are available, and I'll include my notes to clarify how I translated some of the new abilities.
2. None of the classes in the book has multiple attacks per round. I purposely excluded this as an ability - while it's mentioned in both B/X and OSE, it's an optional rule that isn't available until after 14th level and therefore does not impact base XP values. However, I do include multiple attacks as a possible result for high-level characters in Appendix H.

If you wanted to include multiple attacks, I'd suggest an approach similar to learned skills (pg. 68), where the XP cost is based on the rate of extra attack gain.

Hope this helps - post here if there's anything else, and thanks for your support! 

Thank you for that info.  I knew I had read something about multi attacks but couldn't remember where.  I'll look at the learned skills and contemplate how much that should cost.  Feel that the rate should be one level up from the learned skill since attacks are a powerful thing and can change a combat quickly.

@evil-jeff - In full disclosure, I'm not a fan of multiple attacks per round at lower levels, but if I were a fan, I'd start with some working assumptions:

1. What's the max number of attacks/round a class could have (let's say 3... crazy)
2. Assign max number of attacks/round to highest level class can achieve (let's say 14)
3. Disregard any crunch factors for weapon type, size, weight, damage, etc. 
4. Exclude any qualifying requirements (e.g., proficiency)
5. Similarly, let's limit the ability to attacks per round only, meaning no to-hit or damage bonuses - those are separate abilities with separate XP costs

From there, you can create a table showing attacks per round by level. For example:

Level    Att/Rnd
1-6      1
7-12     2
13+      3

The base XP cost for most non-magical abilities is 200XP, but this seems to warrant an increase - I'd double it to 400XP or maybe even quadruple to 800XP. From there, you can extrapolate the cost of a lower improvement rate (and you can ignore a higher improvement rate, because that's where you started).

Hi, I really love this book. Have you tried to work out the cost of the OSE Bard. I'm struggling with the Fascinate/Charm effects of music and the languages ability.

@dextolen - I looked closely at the OSE Bard and broke out the abilities based on the Class Builder:

Basic Abilities [XP Cost = 1,900]

• Prime Requisite: 1 [100]
• Hit Dice: d6 [600]
• Armour: Restricted [100]
• Shield: No [0]
• Weapons: Restricted [100]
• Languages: Alignment, Common, +6 additional [600]
• Combat Progression: As cleric/thief [200]
• Saving Throws: As thief [200]

Special Abilities [XP Cost = 1,800]

• Immunity: song-based magical effects, beguiling powers of fey [400]
• Skill, innate: Lore [200]  
• Spell Casting: Divine spells (max spell level = 4) [400]
• Spells, bonus: Enchantment ~ charm person (lvl 1), animal friendship (lvl 1), charm monster (lvl 4) [600]
• Using Magic Items: As cleric [200]

OSE Bard songs affect persons at 1st level, animals at 4th level, and monsters at 7th level. I've taken the easy route and equated these to existing spells (Charm Person, Animal Friendship, and Charm Monster), which comes out to 6 bonus spell levels, thus 600XP for a spell caster.  

Restrictions [XP Cost = -1,700]

• Requirements: DEX, INT [-200]
• Max Level: 14 [0]
• Stronghold Level: 11 [-1,100]
• Size: n/a [0]
• Equipment: Instrument or holy symbol (?) [-100]
• Pledge: Deity disfavour [-300]
• Weakness: n/a [0]

Assuming I got all the bits, the Class Builder gives me a base XP of 2,000 and the level progression looks to be that of a fighter. 

Let me know if this helps answer your question. 

Cheers!

@erin-smale - This is very helpful.  Please consider doing more of those OSE Adv. classes, I feel that some break the rules (LOL)

@dextolen - Heh... As you point out, "rules" is quite misleading... ? 

The biggest challenge with the OSE Advanced classes is how to translate their abilities - you still gotta eyeball 'em in some cases. For example, the OSE Advanced barbarian gets "Agile Fighting," while the Class Builder barbarian gets "Dodge." Obviously, both are meant to reflect the Conan-archetype by man-handling the character's AC adjustment.

The OSE version is a flat bonus that maxes out at +4 AC at 10th level. I could translate this to the Class Builder's Defensive Bonus ability, which costs 100 XP per point of AC. Normally, that's 400XP. However, Defensive Bonus stipulates "predefined circumstances or against specific foes," and since Agile Fighting is "always on," I'd consider doubling that to 800XP.* 

The Class Builder's barbarian improves their DEX adjustment to AC based on the type of armour they're wearing (x3 for no armour or x2 if wearing chain). This isn't a flat AC bonus- it varies by the character's DEX. In fact, it only helps is the PC has a DEX of 13+. So here's how I eyeballed it: Start with Defensive Bonus (100XP / point of AC), and figure the average AC bonus would be +2 (200XP); it's "always on," so double it (400XP), but not every barbarian character can take advantage of it, so halve it (200XP). 

How an ability manifests affects how well it translates to a Class Builder ability, so as a referee, you may have to adjust up or down. Yet, as an interesting side note, you'll see that both the Class Builder and OSE Advanced versions of the barbarian have a base XP of 2,500. ? 

* Fun fact: When adjusting special ability XP costs, halve if use if further restricted or double if an existing restriction is ignored. This isn't written down anywhere, but it's a good rule of thumb.  

@erin-smale It's been a while and I was going through some notes and came across one that mentioned the worksheets for the classes in the Class Builder book.  Any further word on them?  Also, you had made mention about someone working on an Excel sheet for the book.  How has that come along?

@evil-jeff - Unfortunately, very little traction on either front. Entirely my fault for poor time management. 

On the plus side, I've been thinking about using this forum for not only posting the worksheets, but also addenda to the Class Builder book (new special abilities and restrictions, guidelines for creating your own, and potentially new classes).

Worksheets will be bundled as a PDF and sent to existing customers via DTRPG.

I'm wrapping up a fairly intensive project at work in early April, after which I can return to this commitment - look for better progress from my lazy ass next month.

@erin-smale I hear ya!  I know I hit this past Sept. and lost a huge amount of momentum with things just trying to keep what mattered going through this pandemic, I can only imagine that you and others did the same.

Addenda to the book, here?  Please, give me a reason to come here on a daily basis.  ?

I may put up my worksheet that I use for doing my calculations for some of the classes that I've incorporated for my game.  At least let someone else comment on it.