In my quest to find a viable feinting build I have looked at Improved Two-Weapon Feint (UC) and the Moonlight Stalker feat chain (UC). Since these are the only ways to get a full attack while feinting.
Overall I found that Improved Two-Weapon Feint starts too late (level 8-9) to be useful at all and loses a very valuable attack making it questionable to use at all. I put a lot of emphasis on getting something to work early, preferably around level 5-6 it should come together otherwise it may never see play or get used very rarely before the campagin inevitably ends. As such I abandoned ITWFeint for Moonlight Stalker Feint which grants feint as a swift action.
The base class used was a Ninja as Rogues are not as fun, and Vivisectionist gives up smoke bombs for sneak attack.
Race:
The race is relevant in that Moonlight stalker requires low-light vision or dark vision, there are a few classes and archetypes that grant this but they require two or three level dips.
Half-Orc, +2 bonus to one ability score
This is my preferred choice as you can put the bonus to Strength for to-hit and it comes with Darkvision, the best vision. In addition half-orc can qualify for Keen Scent, allowing you more easily locate enemies within a fog cloud. Plus Scent is a very cool ability. Keen Scent will cost you in the point buy, meaning you can't dump Wisdom as it requires 13, bad for min-maxers but nice for people who hate dumping anything especially Wisdom due to perception and will saves.
Half-Elf, +2 bonus to one ability score
A solid choice but the racial abilities to this class leave much to be desired, choose if you don't like half-orc.
Elf, -2 Str +2 Dex +2 Int
You lose strength and gain intelligence and dexterity, you don't need intelligence beyond qualifying for Combat Expertise, I would skip it.
Gnome, -2 Str +2 Dex +2 Cha
The lost strength really hurts, and you don't need very much charisma since you will, in an ideal situation, use all your ki for smoke bombs.
Dwarf, +2 Con +2 Wis -2 Cha
The charisma penalty hurts your ki, which will be limited due to MAD, though you only really need it for smoke bombs. The other stat bonuses don't hit strength, I can't see this race doing well at an already tough build.
Point buys:
I place a lot of emphasis on strength because I think that weapon finesse for rogues is a trap, costing a feat to get dex to hit only to lose out on damage anyways and Dervish Dance is a questionable feat outside the core books that also restricts weapon choice. One build assumes Keen Scent for a half-orc which requires 13 Wisdom, feel free to dump it but I think some kind of blindsense ability is necesary when fighting in fog.
Since you are fighting in fog you will have concealment and total concealment from most enemies, therefore you could potentially dump dexterity. If you take a couple levels of Lore Warden, as you can make up the lost AC with Full Plate which doesn't intefere with any Ninja class ability though it may hurt your stealth checks and mobility a bit.
Point Buy(20): with Keen Scent (Oh lordy look at that MAD)
17 Str Racial +2
12 Dex
13 Con
13 Int
13 Wis
12 Cha
Point Buy (20): without Keen Scent
19 Str Racial +2
12 Dex
12 Con
13 Int
8 Wis
12 Cha
All level-up points should go to strength because you need to stay combat viable.
Feats:
I have two separate paths here one for straight Ninja, the other uses two levels of Lorewarden to ease the required number of feats since this build uses a lot of feats to get going. Lorewarden also grants Martial and Heavy Armor proficiencies allowing for free choice of weapon and armor, that way you never miss out on the randomly looted awesome sword or armor that doesn't fit your feats.
In the straight ninja build you can't really use your ninja tricks for anything but Smoke Bomb and Combat Feats (thanks to the Combat Trick), but smoke bombs are pretty cool.
In the Lore Warden build you take Lore Warden as your first two levels, which delays smoke bomb and sneak attack but you can fit in Keen Scent or any other feat you fancy at level 1. You can also pick any feat at level 4 though I prefer Power Attack since this is a combat focused build using preferably a two-handed weapon.
In combat your first job is to hit them with a smoke bomb, this could cause issues since your party may not want to fight in fog, but usually the baddies will attempt to get out of the fog so they can fight back. This could have the benefit of blocking enemy archers/wizards and splitting up enemies, if an enemy stops just outside of the fog then you will still have concealment 5 feet away in the fog.
When attacking, you will start off with a swift feint at level 6(this means no extra ki attack as that also uses swift actions), this should be rather easy as most monsters don't have high wisdom, throw in a circlet of persuasion and a masterwork bluff tool (a flashy cloak might suffice) for a +15 at level 6 which should succeed against even level opponents, a wondrous item of bluff for +5 circumstance bonus would probably cost about 2500 gold. It isn't perfect but should be reliable enough.
If you are surprised you can smoke bomb with the enemy on top of you and give your party full/partial concealment to buff and prepare to counterattack, watch out for fireballs though as they will blow away your cloud. Remember that you are still capable of combat outside the fog: with flanking or move action feinting at level 7+.
Before level 6 you won't be able to easily feint and attack but you still benefit from Moonlight Stalker's +2 to hit and damage for fighting in the smoke bomb's cloud, or any kind of concealment including darkness, foliage, or heavy snowfall.
Overall it's far from a perfect sneak attack build and may not even be viable, if there is any interest I will expand on my decisions and choices. I probably won't get a chance to play this build in the near future but there was a complete lack of Moonlight Stalker builds and especially Ninja builds on these boards.
Let me know what you think, what you would change, and where you might take a similar build.
Side Notes:
-Moonlight Feint is a swift action so you won't benefit for the Ki Pool extra attack on the same turn, but haste would be really good to have.
-Feint does not count for ranged attacks so I did not touch on it, but that would be so cool if it did.
-If my math is correct attacking through 20% concealment shouldn't be an issue with Blind Fight since you will only have a 4% chance of missing due to concealment. You're more likely to roll a critical miss than miss due to partial concealment.
I personally have been looking over an alchemist vivisectionist build that uses the battle poi.
The idea (and where the problem is too) is to use the poison conversion ability to turn poisons into inhaled type and soak the battle poi on that. Now of itself the battle poi won't produce enough smoke to give the concealment you want, so the next process is to add a smokestick into the battle poi itself (somehow) in order to get a nice big cloud of smoke around you in addition to the poison. The problem (obviously enough to me) is the fact that this idea while feasible in spirit could run into problems on the RAW end and with a GM that doesn't like the idea.
I personally have been looking over an alchemist vivisectionist build that uses the battle poi.
The idea (and where the problem is too) is to use the poison conversion ability to turn poisons into inhaled type and soak the battle poi on that. Now of itself the battle poi won't produce enough smoke to give the concealment you want, so the next process is to add a smokestick into the battle poi itself (somehow) in order to get a nice big cloud of smoke around you in addition to the poison. The problem (obviously enough to me) is the fact that this idea while feasible in spirit could run into problems on the RAW end and with a GM that doesn't like the idea.
The battle poi is an unusual weapon, it says it is a pair of chains that counts as having two-weapon fighting but it isn't listed as a double weapon on d20pfsrd.com. Probably an error on the srd though. Attaching an inhaled poison seems to be a stretch though a contact poison might work just a well. I thought there was a holy sprinkler mace that had holes to spray holy water when it hit but I guess not, designing weapon like that with smokesticks could be pretty cool and allow for a vivisectionist to go moonlight stalker.
I know there's a mistmail shirt in the 3.5 MIC that grants concealment in your square without blocking your own sight, it's of course 3.5 material and a swift action so it interferes with feinting. Similarly there is the Mistmail from pathfinder that forms a fog that follows the character providing concealment but you lose your armor bonus temporarily.
You get a free use of two weapon fighting with it -- unfortunately it's an one handed weapon as listed, so the penalties are harsh -- that's part of the reason I went with the alchemist instead of rogue or ninja. Since you get the two weapon fighting feat (and only that one) for free you can strength focus instead of dexterity focus and use a mutagen to help keep the damage up.
The idea isn't to use the poison for contact -- it's to burn it into the smoke cloud -- every round you are beside them they'll take at least two doses of inhaled poison at the same time (from breathing in the cloud and you having two battle poi) -- eventually a 1 will get them if nothing else, and you are piling on doses each round simply being beside them -- basically its a fall back to hitting, they have to breath, and regardless of you hitting the poison will hopefully hurt them.
The nice thing about using alchemist is you can still use another discovery to get the feral extract to have another means of attack to fall back on. Battle poi (and all the damage they'll do with sneak attack) are going to do fire damage... and only fire damage so you'll want to make sure you have another weapon to fall back on (which again feral mutagen works into nicely).
You can only take each trick once unless the trick specifies that you can take it multiple times.
"As a ninja continues her training, she learns a number of tricks that allow her to confuse her foes and grant her supernatural abilities. Starting at 2nd level, a ninja gains one ninja trick. She gains one additional ninja trick for every 2 levels attained after 2nd. Unless otherwise noted, a ninja cannot select an individual ninja trick more than once. "
I believe that Deadly Range and Rogue Talent are the only Ninja Tricks that specify they can be taken more than once.
