While in theory do-able; I think it would be WAY easy to make them overpowered. Any time you add a bonus to a bonus, it gets dangerous
The reason is because it leads to specialization, and since you are only playing one person, and not the whole race, it never balances out.
For instance, you pick a race that gets a +2 dex to be a thief. Well, as they go up in 'race' levels, they get another +4 dex, -2 str, -1 con, -1 wis. For the race as a whole, this mostly balances out. But since you are only playing one thief, it is pretty much all benefit.
It can be done, and could be cool, just make sure the disadvantages in theory, are also disadvantages in practice.
I would lean more towards PrC's that have a racial pre-req.
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The reason is because it leads to specialization, and since you are only playing one person, and not the whole race, it never balances out.
For instance, you pick a race that gets a +2 dex to be a thief. Well, as they go up in 'race' levels, they get another +4 dex, -2 str, -1 con, -1 wis. For the race as a whole, this mostly balances out. But since you are only playing one thief, it is pretty much all benefit.
It can be done, and could be cool, just make sure the disadvantages in theory, are also disadvantages in practice.
I would lean more towards PrC's that have a racial pre-req.
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