Skip the bit in the block below if you don't care about the lead up to the question and want to get straight to the crunch.
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Okay, a while back I was playing around with a tiefling rogue/ninja more to figure out how to mix and match natural weapons with unarmed attacks than anything else. Did a few generic test characters, never really took it anywhere.
But I've been playing a lot of Disgaea 5 here lately, and the lead character in it is basically a demon monk (primarily fights with bare fists), and it started reminding me of that tiefling claw/UAS character, so I've been going over some of the more fluff bits in my head to round out an actual character instead of just a build.
Also have been interested in finding good ways to reflavor the oriental background flavor out of the Ninja class to be more acceptable in a western-centric game. They make great assassins and the like, but wanted something more acceptable for an average PC than an assassin.
Looked at the tiefling, mourned that they couldn't get full wings like an Assimar can in PF, and glanced through Favored Class bonuses. Rogue: +1/2 to Sneak Attack damage per level against Outsiders, and Ninja is basically just an alternate Rogue, so that would still apply.
Bam, he's a demon hunter! All the ki tricks and supernatural stuff he does isn't a result of being a Ninja, its a result of him being half-demon who fights fire with fire! Shadow clones are a lot easier to accept with the idea of them being demonic power than they are Naruto jujitsu stuff.
Could even work with the DM so that when I level up and take a particularly supernatural Ki trick I could fight something demonic that has a similar power and "absorb" it to learn it for myself (aka, thats the fight I level up on, and use it as justification for why I suddenly became able to make shadow clones of myself).
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Okay, so we have a premise, tiefling demon hunter who has demonic abilities (aka, ninja ki powers and tricks) and hunts "his own kind". Likely going to go with claws and unarmed strikes mixed and matched (claws first at the lower levels, then put in improved UAS with the claws becoming secondary natural weapons later on) to be a nice little flurry of demon ripping death.
What I'd like to do is add in a few extra twists that one wouldn't necessarily expect, or that help to drive the demon hunter aspect home, but I'd like to keep it as straight Ninja if possible.
First thought was "I need some kind of Favored Enemy style thing for demons/evil outsiders". Quick internet search turned up a Demon Hunter(combat) feat from a book I don't have that was basically +2 to attack rolls against demons, and thats kind of like a watered down Favored Enemy. I'd like a little more focus there if possible though, without having to go into a full on Ranger dip just for the one Favored Enemy.
Second thought was "What if his blood really gets boiling when fighting demons, like Barbarian Rage where he just really gets into it specifically against them?" Thing is, rage like mechanics are really hard to come across outside of being a Barbarian, and again not to keen on dipping into every class under the sun if I can avoid it.
Anyone with ideas on how to give it unexpected mechanical twists, like watered down versions of other class abilities beyond what I can do with Tricks/Talents?
If I do end up dipping, have been looking at Urban Barbarian for their Controlled Rage, or perhaps even Monk to make use of Monk's Robes for all the unarmed strikes. Gotta admit just the flavor of going Qinggong Monk and picking up Scorching Ray sounds pretty nice even if it doesn't end up being all that mechanically powerful. Demons shooting fire and all that.