Warrior and Divine have things they can give up for extra abilities. Fighter 2 or higher characters add to their xp cost when they do this but Divine does not.
Thief is nothing but custom abilities.
Arcane has nothing to swap.
However, Fighter 0 DOES have a sneaky thing to give up…a fighting style (two handed). Doing so is what the Warlock does resulting in only being able to use a staff one handed (d4). But otherwise you lose little by sacrificing this ability. If you held off your acquisition of detect evil till a higher level than first you could even get two powers or more out of it.
Of course, that allows for a trade in. If I wanted to add to a base class like the races do, I have to add racial build points. There doesn’t seem to be a set cost for those, although the Ruinguard seems to imply a cost of 500 xp per ‘special ability’, which could itself be trade in for extra powers at later levels.
Is that the way to go?
Perhaps it would be better to decribe my purpose here: I’d like to de-elf the elven enchanter - retain the class powers, but drop the elven racial powers. I’d also like to add infravision, and a bonus to saves vs poison. I have no idea how to make an elven class into a human class, so I figured a simple example (the mage thing above) would be the best way to establish a baseline…
Human classes don’t get to just add powers for an XP cost. (Technically, neither do nonhumans).
There are a couple of approaches to what you want to do. My preferred take would be to trade off the fighting style for some of the powers you like at higher level, and then make the other powers available through your custom class’s proficiency list.
Another option is to make a custom race with the additional powers you like at Race 0 (plus optionally the Nobiran power that increases their max level by 1 so that Race 0 plus Arcane 4 can hit level 14 if you want). Flavor this race as a god-blooded or spirit-touched or something, or just pretend it’s part of the class rather than race.
Somewhere buried in an old thread is a post by Alex on how to make custom races, but I’ve lost the link. Here’s the basics, though:
Calculate number of racial powers.
Subtract 1, to represent the fact that racial classes lose 1 maximum level of experience at Race 0.
Add 1 if the class has racial value powers at 1+ that are not available to humans.
Multiply the result by 40.
Round the product to the nearest interval of 25 (25, 50, 75, 100, 125, etc.)
If the race’s racial value mimics a class (such as elf and mage), divide the Racial Value XP cost at Value 4 by the cost for elf 4 (2,625) and multiply the result by 50,000. This is the additional cost per level after 8.
If the race’s racial value does not mimic a class (such as dwarf), divide the Racial Value XP cost at Value 4 by the cost for dwarf 4 (1,400) and multiply the result by 10,000 for 2 class types and 30,000 for 2 class types. This is the additional cost per level after 8.
Yeah, what Witness said. There is no way to make a human that has those abilities and keep full casting.
You could make an Enchanter and do it like the Warlock (Arcane-3, Thief-1). With the trade off of Fighting 0 you have 4 custom abilities to play with. You advance faster than a pure wizard but with less spells. With 4 customs, you could easily buy the 3 elven enchanter abilities, and then maybe delay the gaining of infravision and poison immunity.