Yeah, I'm aware of soul's gross advantages, I just think they'll turn out vastly weaker in actual play. To consider an example, say we want to raise Chakra Control. How many people do we know of for whom Chakra Control is the #1 highest Skill, who we would have a reasonable shot at killing?
...Sakura? I can't think of anyone else.
The clan ninjas probably all specialize in clan-specific stuff, so we would have to Itachi them to get to a good level. Search is actually going to be a huge issue. We can't just kill willy-nilly because the technique requires us to stand over their corpse for several minutes afterwards, completely vulnerable, which rules out using it in the midst of combat.
If we kill in an un-focused fashion without target research, we'll end up with a large number of level 1 Skills that could have been bought for 1 xp anyway. Remember, specific Taijutsu styles are individual skills, and each technique is an individual skill. Most high-level techniques probably aren't even useful unless they're high-level.
If we kill in a focused fashion, we run into the problem of search. How many people are 1) stronger than us in our skill of choice, but 2) weak enough to feasibly kill, with 3) that
specific skill as their highest, in 4) our reasonable search radius, that 5) we can kill and stand over their corpse for several minutes without drawing massive sociopolitical consequences? That pretty much rules out all Konoha ninja, so our only valid targets are other missing nin? Conditions 1 + 2 are hard enough to satisfy. Add in 3 and 4 and it looks daunting. Condition 5 on top of all that makes it look like a pipe dream. It's basically a power we can't profitably use unless the GMs dole out favorable circumstances by fiat, until we're jounin-level and able to defy established power structures.
And, of course, that's leaving out the problematic characterization such a shinobi would require. I don't want to play a total sociopath!
Correct me if I'm wrong, but
messing around in AnyDice it seems every skill rank of difference changes the average by about +-50, and higher total skill levels only increase how far from the average we can expect to go (standard deviation). Going by what
@eaglejarl said
about the dice mechanics, that means a single rank of difference averages a critical success, and two or more ranks are double or more that.
We're already looking a decisive victories for a single rank, and if we're expecting chunin/jonin hunter-nin after us at any point... well, I guess my question is, can we expect to have a chance at existing after our homeland figures out we're not already dead? If they send even a single jonin with better Stealth and Awareness skills then than anyone on our team, how do we avoid Game Over?
After all, our highest jonin are disposable enough to be sent on a suicide mission
en masse, and if the skills are that far apart at the top, it seems like they should have a least a single Jonin that can wipe the floor with our entire team.
It should be (32.5/50), not (13/50), no?
I would just like to point out on the Stealth Assassin build that the proposed bloodline hardly seems worth 30 points to me. It applies a nerfed ability to learn how to do physical motions, and only if there's someone who is already better and capable of doing those motions doing these motions in ideal viewing conditions. We can't do it mid-fight, we can't do it if it's foggy or raining, and we have to see it done multiple times before we can do it ourselves.
While it sounds good on paper, I fear the strict conditions on the Iron Nerve bloodline would make it markedly less useful than either potentially Sage level chakra sensing or perfect internal chakra control.
It doesn't have anything to do with observation, what it does is let you recall and replicate any physical movement you've successfully performed before. It's not a crappy Sharingan, it's like if someone took the motor-cortex interface of the Sharingan and turned it recursively in on itself, while integrating it into the full nervous system.