How do I tell if a Homebrew Race is balanced properly?

Question

I recently created a homebrewed pair of related races based on Steven Universe (a Gem and Half-Gem race), but I could not tell how properly balanced they were. According to The Race builder they should be, but at the same time I had to interpret my own numbers. I also had to take an educated guess at the RP values of some homebrewed abilities (Gem Weapon and Gem Reformation) as I don't think there are any similar abilities in the race builder. To make up for that I used a high estimate of their RP value.

Now that I have my two races written up, how do I tell if they're actually balanced?

Answer 1

Playtesting.

I know it's somewhat of an unsatisfying answer, but it's the truth. It's what all of the professionals do when they make a new class or race or what have you. The rest of my answer is taken from paid game developer's answers at conventions I've attended (with some of my own experience).

It's good that you have data from an external system that says they're balanced. If you have a system junkie friend who can look over your work, that's good too.

Build a few characters at different stages in their progression. Build at least one per for each of the race's key classes, and at least one class that's outside their core competence (example: Dwarven Rogue). At this time, compare the character sheets to other builds, check for way out-of-whack bonuses and things like that.

Mix them into some parties. If you have modules with pregenerated characters, awesome. If you don't, then you'll need to dig up some of your old encounters. Swap out one or two of the original characters for of your experimental ones.

Play out the scenarios. If your characters are painfully imbalanced, it'll be obvious pretty quickly. If they're only slightly imbalanced, that'll come out later when other people actually play the races.

Answer 2

The Creating New Races rules are quite comprehensive and I think trouble in trying to value something like being able to summon a weapon is expecting an ability to appear almost exactly like that as a Racial Trait. What you describe sounds more like a spell which you can have as a Racial Trait, I'll point you to the Magical Racial Trait, Standard "Spell-Like Ability, Lesser" of the Creating New Races rules that were linked above:

Spell-Like Ability, Lesser (Variable, see Special)

Prerequisites: None. Benefit: Choose a 2nd-level or lower spell that does not attack a creature or deal damage. Members of this race can use this spell as a spell-like ability once per day. The caster level of the spell is equal to the user's character level.

Special: This trait costs as many RP as the level of the spell chosen (minimum 1RP). This trait can be taken up to three times. Each time you take an additional spell, adjust the RP cost of this trait appropriately.

This is how you should calculate such a racial ability LIKE summoning some sort of energy based weapon. Look through all the spells of all the caster classes and look for any spell which replicates close enough the effect you had in mind. And the rules for duration of that spell and how much this spell-like-ability costs will tell you how it is balanced.

I don't know what spell that might be, perhaps Umbral Weapon? This ability could just exist exactly as the rules say it is, as a spell-like-ability.

Remember, spell-like-abilities still lack most of the qualities of a spell such as somatic/verbal/material components or armour % fail chance, you just have to make a concentration check and they provoke to cast.