Rogue (Knife Master); Human - Full Writeup

Self-Interested Preface: This was the second build I got serious about- I did a full writeup of the character and its capabilities to help myself understand Pathfinder and the character's role in an upcoming campaign.  There could easily be inaccuracies, and it's likely I'd change some things if I built it today, but like with the skinwalker barbarian, I'm not prepared to sit down and revamp a build right now.  Hopefully this at least helps someone looking for ideas, and if anyone has any suggestions or corrections, let me know!

Build created in July of 2015.

The Knife Master is an extremely powerful archetype when doing what it does best, and keeps a steady progression which allows it to stay consistently relevant.  It trades trapfinding, trap sense and regular sneak attacks for improved concealment of dagger-sized weapons, a bonus to dodging light blades, and a 1d8 sneak attack with daggerlike weapons, which is the offsetting factor that makes the knife master such a powerful combat build.  In campaigns you expect to be trap-heavy or if your party absolutely NEEDS a rogue’s class bonus to disabling traps and ability to disarm magical ones, the knife master is a poor choice- the rest of the time, it’s a rogue with an xd8 sneak attack and an extra dodge bonus against an entire group* of weapons.

* Light blades: bayonet, butterfly knife, butterfly sword, chakram, dagger, gladius, hunga munga, kama, katar, kerambit, kukri, madu, pata, quadrens, rapier, sawtooth sabre, scizore, shortsword, sica, sickle, starknife, swordbreaker dagger, sword cane, wakizashi, and war razor.

Race is Human for the +2 to ability score of your choice (DEX) and especially the bonus feat and 1/6 rogue talent to get ahead of the curve.  The build is feat-intensive, with about half of its feats and talents going toward improving defense and saving throws.  I’ve heard too many horror stories of the traditionally low-Will rogues and fighters in a party falling under a dominate or compulsion and turning a tough encounter into a potential TPK.  This build will never be immune to enchantment, but it’ll have a fighting chance from the beginning.  I also suggest Heart Of The Streets over Skilled for an extra +1 Reflex and +1 AC when adjacent to allies.

The traits I suggest are Latent Psion (Human, Legacy Of Fire), which gives a +2 against mind-affecting spells, and Heirloom Weapon: Kukri, to gain proficiency with what’s effectively a slashing dagger with an 18-20 critical range.  A keen or improved-critical kukri has a 15-20 critical range, and since this is a two-weapon fighting build, you’ll eventually average one to two critical hits every round.  If your DM allows it, take a drawback and get Strong Willed (Religion, Faiths Of Purity), which gives a further +2 against charm and compulsion.

Point Buy 15                                       Point Buy 20                                       Point Buy 25  

STR     10                                            STR     10                                            STR     10       

DEX    15+2 (17)                                DEX    16+2 (18)                                DEX    16+2 (18)

CON   14                                            CON   14                                            CON   16       

INT      13                                            INT      14                                            INT      14 

WIS     10                                            WIS     10                                            WIS     10

CHR    10                                            CHR    10                                            CHR    10

Note: For the purposes of this build I will assume a 20-point buy.

Strength is only important for carrying things, and since you’re using light weapons and light armor, you don’t have much to carry.  Slashing grace at level seven allows you to add your DEX to damage, as does the Agile enchantment, but they do not stack.

Dexterity is of prime importance, though it could be reduced to boost CON for extra hitpoints and Fortitude.  With your Finesse rogue talent, obtained at level two, DEX determines your attack bonus and with an agile weapon makes STR obsolete.

Constitution is of secondary importance, determining your hitpoints and boosting your Fortitude saves.  As a rogue, your hit die is only 1d8, which can feel dangerously low since, after your first sneak attack, you are effectively a front-line combatant.  CON should be either 14 or 16.

Intelligence is necessary for Combat Expertise, which is your defensive always-on combat feat.  It’s not absolutely necessary it be at 14 rather than 13, but the staggering amount of class skills a rogue has give your skill points a lot of versatility.

Wisdom is important to boost Will saves, but that’s it.  As I mentioned previously, a domination on a powerful character, especially this one can mean a fast death for other party members, but feats and traits boost Will more efficiently.  I’m comfortable just bringing WIS out of the negatives with this build.

Charisma is 10 specifically to keep your Bluff and Use Magic Device skills from being any lower than they have to be.  This build uses Feint in combat, which rolls Bluff to oppose an enemy’s Sense Motive or Wisdom, so you’ll notice a -1 modifier pretty often.  I wouldn’t raise it above 10 in this build, even as the party’s face.

The rogue’s class skills are Acrobatics, Appraise, Bluff, Climb, Craft (Any), Diplomacy, Disable Device, Disguise, Escape Artist, Intimidate, Knowledge (Dungeoneering), Knowledge (Local), Linguistics, Perception, Perform, Profession, Sense Motive, Sleight of Hand, Stealth, Swim, and Use Magic Device.  Since the rogue class gives you eight skill points plus your INT modifier to play with, you have some flexibility regarding your role in the group.  Regardless of what you intend to do, I recommend maxing out Acrobatics, Bluff, Perception, Stealth and Use Magic Device.  Acrobatics will keep you safe while moving in combat, Bluff is for feinting in combat which is the entire point of this build, Perception is the most commonly-rolled skill in the game, Stealth is for getting a first strike in (potentially killing an enemy mage before combat even begins!), and Use Magic Device makes wands useful, giving a rogue some low-level spell options (including healing).

A rogue at first level gets 140 GP.  I recommend purchasing: two kukri with weapon cords (16 GP, 2 sp; 2 lbs.), a chain shirt (100 GP; 25 lbs.), 20 darts (1 GP; 1 lb.), a small steel mirror (10 GP; ½ lb.), 5 trail rations (25 SP; 5 lbs.), and 10 candles (10 CP; - lbs.).  You have 33 lbs. before you’re at medium encumbrance at 10 STR, so keep that in mind if you or your GM is precise about encumbrance.

Here’s a breakdown of the build, level by level:

1: Rogue (Knife Master) 1, 1d8 Hit Points per level, +1/6 Rogue talent, 10 Hit Points

            BAB: +0

            AC: 18 (10+4 DEX+4 chain shirt), 19 with Combat Expertise

            Saves: +2/+7/+0

Feats: Simple Weapon Proficiency, Rogue Weapon Proficiency, Light Armor Proficiency, Hidden Blade (+1 Sleight of Hand to conceal light blade), Sneak Stab (dagger, kerambit, kukri, punching daggers, starknife, or swordbreaker dagger), [1^st Level Feat] Two-Weapon Fighting, [Human Feat] Combat Expertise

Skills(10): Acrobatics, Bluff, Perception, Stealth, Use Magic Device, +5 others

            Sneak Attack: +1d4 / +1d8 with daggerlike weapons

            Unenhanced Full-Attack Action(darts): +4

            Unenhanced Full-Attack Action(one kukri): +0

            Unenhanced Full-Attack Action(two kukri): -2/-2 (haha what)

At first level you’ve taken Two-Weapon Fighting, which you shouldn’t be using until second level, and Combat Expertise, which you’ll be using in most melee combat encounters (and is required for Two-Weapon Feint).  Without the Finesse rogue talent, you’re not very accurate in melee, though with the kukri you have a higher chance of critical hits and if you can flank with an ally, you’ll get +2 attack and will do an extra 1d8 damage.  You throw darts at +4, which have a 20’ range increment and do 1d4 piercing damage.  Your Will seems pathetic at +0, but against sleep it’s actually a +4 and against charm person it’s a +9.  Acrobatics and Stealth are usable, with +6 to each after the chain shirt’s penalty.  So far, you’re not much better than any other rogue.

2: Rogue (Knife Master) 2, +1/6 Rogue talent, base Hit Point range 11-18

            BAB: +1

            Saves: +2/+8/+0

Feats: Evasion, Rogue Talent: Finesse

Unenhanced Full-Attack Action(darts): +5

            Unenhanced Full-Attack Action(one kukri): +5

            Unenhanced Full-Attack Action(two kukri): +3/+3

Now you’ve got Finesse and Evasion, and since your Reflex save stays high it’ll hopefully negate any fireballs and lightning bolts aimed in your direction.  You attack at +3/+3 (+2/+2 with Combat Expertise) which is a massive +5 attack bonus since level one, making you a viable melee combatant.

Note: To save space, I’m not going to denote most of the fields that do not change between levels (namely Skills).

3: Rogue (Knife Master) 3, +1/6 Rogue talent, base Hit Point range 12-26

            BAB: +2

AC: 18 (10+4 DEX+4 chain shirt), 19 with Combat Expertise, +1 against light blades

            Saves: +3/+8/+3

Feats: Blade Sense (+1 AC against light blades), [3^rd Level Feat] Iron Will

            Sneak Attack: +2d4 / +2d8 with daggerlike weapons

Unenhanced Full-Attack Action(darts): +6

            Unenhanced Full-Attack Action(one kukri): +6

            Unenhanced Full-Attack Action(two kukri): +4/+4

You have your first +1 against light blades, and Iron Will boosts Will saves by a flat +2 in addition to the natural +1 weak save progression, which means against Sleep it’s actually a +7 and against Charm Person it’s a +11 to save.  A harpy’s song has a DC of 16, so with your +7 (it’s a mind-affecting charm ability) you now only have to roll a 9 or higher to resist it.

4: Rogue (Knife Master) 4, +1/6 Rogue talent, base Hit Point range 13-34

            BAB: +3

            Saves: +3/+9/+3

            Increased Ability Score: DEX +1 (19)

Feats: Hidden Blade (+2), Uncanny Dodge, Rogue Talent: Combat Trick (Two-Weapon Feint)

Unenhanced Full-Attack Action(darts): +7

            Unenhanced Full-Attack Action(one kukri): +7

            Unenhanced Full-Attack Action(two kukri): +5/+5

The rogue’s ¾ BAB progression is still improving combat at a comfortable pace.  At fourth level, with Two-Weapon Feint you now have the ability to forego your first melee attack to make your second a sneak attack, which you’ll want to do any time you’re not flanking or coming out of stealth.  As quickly as possible, you’ll want to pick up the Mask Of Stony Demeanor, a 500 GP item that grants +5 Bluff (!) when feinting.

Level five looks like this:

5: Rogue (Knife Master) 5, +1/6 Rogue talent, base Hit Point range 19-47

Feats: [5^th Level Feat] Toughness

            Sneak Attack: +3d4 / +3d8 with daggerlike weapons

Even if you don’t find yourself taking very much hit point damage, take Toughness anyway.  It’s for you, I promise.

6: Rogue (Knife Master) 6, +1/6 Rogue talent, base Hit Point range 21-56

            BAB: +4

AC: 18 (10+4 DEX+4 chain shirt), 20 with Combat Expertise, +2 against light blades, +3 for one round after sneak attacking

            Saves: +4/+10/+4

Feats: Hidden Blade (+3), Blade Sense (+2), Rogue Talent: Offensive Defense, [Favored Class Bonus] Rogue Talent: Weapon Training (Weapon Focus: Kukri)

Unenhanced Full-Attack Action(darts): +8

            Unenhanced Full-Attack Action(one kukri): +9

            Unenhanced Full-Attack Action(two kukri): +7/+7

A huge boost in defensive capability- Combat Expertise improves to +2 AC/-2 attack and Offensive Defense improves your dodge AC by the amount of sneak attack die you hit an enemy with, which applies to any attack made against you in the next turn, and because of Uncanny Dodge, it’s very difficult to lose your dodge AC.

7: Rogue (Knife Master) 7, +1/6 Rogue talent, base Hit Point range 23-65

            BAB: +5

AC: 18 (10+4 DEX+4 chain shirt), 20 with Combat Expertise, +2 against light blades, +4 for one round after sneak attacking

Feats: [7^th Level Feat] Slashing Grace: Kukri Combat Reflexes?

            Sneak Attack: +4d4 / +4d8 with daggerlike weapons

Unenhanced Full-Attack Action(darts): +9

            Unenhanced Full-Attack Action(one kukri): +10

            Unenhanced Full-Attack Action(two kukri): +8/+8

Slashing Grace is intended for swashbucklers and duelists, but it’s perfect for this dexterity-based kukri build.  It adds your DEX instead of STR to damage with one one-handed slashing weapon.  At this level it’s an extra +4 damage, and since it’s replacing your STR modifier, it’s also multiplied on a critical hit, of which you will get many.

Slashing Grace only works with single weapons wielded in one hand, which is fucking lame.  Instead, I recommend getting something like Combat Reflexes and training it out next level for Lunge.

8: Rogue (Knife Master) 8, +1/6 Rogue talent, base Hit Point range 25-74

            BAB: +6/+1

AC: 19 (10+5 DEX+3 leaf armor), 21 with Combat Expertise, +2 against light blades, +4 for one round after sneak attacking

            Saves: +4/+12/+4

            Increased Ability Score: +1 DEX (20)

Feats: Hidden Blade (+4), Improved Uncanny Dodge, [Retrain from Combat Reflexes] Lunge

Unenhanced Full-Attack Action(darts): +11/+6

            Unenhanced Full-Attack Action(one kukri): +12/+7

            Unenhanced Full-Attack Action(two kukri): +10/+10/+5

You now have three attacks!  When fighting multiple enemies, depending on your GM, remember to roll each attack before you declare who you’re attacking, in case you kill an enemy (which you probably often will).  Lunge is an amazingly low-requirement feat that lets you trade 2 AC for 10’ reach.

9: Rogue (Knife Master) 9, +1/6 Rogue talent, base Hit Point range 27-83

            BAB: +6/+1

AC: 19 (10+5 DEX+3 leaf armor), 21 with Combat Expertise, +3 against light blades, +5 for one round after sneak attacking

            Saves: +5/+12/+5

Feats: Blade Sense (+3), [9^th Level Feat] Improved Two-Weapon Feint

            Sneak Attack: +5d4 / +5d8 with daggerlike weapons

            Unenhanced Full-Attack Action(one kukri): +12/+7

            Unenhanced Full-Attack Action(two kukri): +10/+10/+5

Improved Two-Weapon Feint is the most relevant ability you’ll have this whole build.  You use your first attack as a feint and on a success, your opponent is now flat-flooted against all your other attacks for the turn, lowering their AC and eventually giving you up to six sneak attacks(if hasted) against an aware opponent every round.  You are a terror to any enemy without Sense Motive, and since skill rolls don’t necessitate failure on a natural 1, your feint could potentially be an auto-success.  Your feinting bluff bonus at this level with the Mask Of Stony Demeanor is +18, which means any intelligent enemy whose BAB+10+(WIS/Sense Motive) is 19 or lower is auto-feinted.

I will no longer be denoting dart attacks because you’re likely not using darts by now, though they remain an inexpensive, light ranged weapon and it would be good to keep them handy in case all your enemies can fly or something.

10: Rogue (Knife Master) 10, +1/6 Rogue talent, base Hit Point range 29-92

            BAB: +7/+2

            Saves: +5/+13/+5

Feats: Hidden Blade (+5), Advanced Talents, Rogue Talent: Hard-Minded

            Unenhanced Full-Attack Action(one kukri): +13/+8

            Unenhanced Full-Attack Action(two kukri): +11/+11/+6

The first advanced talent you’ll be taking is Hard-Minded, which lets you make a new will save every round you’re under the influence of a mind-affecting effect, even if you’re not supposed to have a will save against it.  With your relatively-high will save and a 5% chance to automatically succeed, this will give you a massive edge against some of the most debilitating effects in the game.  It bears reiterating: if you take ranged or melee damage, you have options, including healing and escape.  If you’re hit with a fortitude- or reflex-save spell, generally you’re under some ill effect or taking extra damage, but the damage is limited to you alone.  If you’re charmed or dominated, you actually become dangerous to your other party members, potentially delimiting the destruction a spell could cause.  With Hard-Minded, you have something you can do about it.

11: Rogue (Knife Master) 11, +1/6 Rogue talent, base Hit Point range 31-101

            BAB: +8/+3

AC: 19 (10+5 DEX+3 leaf armor), 22 with Combat Expertise, +3 against light blades, +6 for one round after sneak attacking

Feats: [11^th Level Feat] Improved Two-Weapon Fighting

            Sneak Attack: +6d4 / +6d8 with daggerlike weapons

            Unenhanced Full-Attack Action(one kukri): +14/+9

            Unenhanced Full-Attack Action(two kukri): +12/+12/+7/+7

You now have four attacks!  A typical round with two unenchanted kukri now ideally goes: feint (1d20+20), attack +12 for 1d4+5(18-20 x2)+6d8, attack +7 for 1d4+2(18-20 x2)+6d8, attack +7 for 1d4+2(18-20 x2)+6d8; but you’re level eleven!  Your kukri are at least +2 by now.

12: Rogue (Knife Master) 12, +1/6 Rogue talent, base Hit Point range 33-110

            BAB: +9/+4

AC: 19 (10+5 DEX+3 leaf armor), 22 with Combat Expertise, +4 against light blades, +6 for one round after sneak attacking

            Saves: +6/+14/+6

Ability Score Increase: +1 DEX (21)

Feats: Hidden Blade (+6), Blade Sense (+4), Rogue Talent: Entanglement Of Blades, [Favored Bonus Feat] Rogue Talent: Crippling Strike

Sneak Attack: +6d4 / +6d8 with daggerlike weapons, 2 STR damage

            Unenhanced Full-Attack Action(one kukri): +15/+10

            Unenhanced Full-Attack Action(two kukri): +13/+13/+8/+8

Entanglement Of Blades is fantastically useful for creatures intending to cast spells in combat, like, say, to escape the rogue who ended up being far more than they could handle.  It keeps enemies hit by your sneak attack from taking 5’ steps, which means they can no longer move out of your range without incurring an attack of opportunity, giving you another sneak attack.  Crippling Strike does STR damage, which is cumulative.

13: Rogue (Knife Master) 13, +1/6 Rogue talent, base Hit Point range 35-119

            BAB: +9/+4

            Saves: +6/+14/+6

Feats: [13^th Level Feat] Combat Reflexes

            Sneak Attack: +7d4 / +7d8 with daggerlike weapons, 2 STR damage

Combat Reflexes gives you an additional amount of attacks of opportunity per round equal to your DEX modifier, which is currently 5 before items.

14: Rogue (Knife Master) 14, +1/6 Rogue talent, base Hit Point range 37-128

            BAB: +10/+5

            Saves: +6/+15/+6

Feats: Hidden Blade (+7), Rogue Talent: Opportunist OR Rogue Talent: (Combat Trick: Lunge)

Unenhanced Full-Attack Action(one kukri): +16/+11

            Unenhanced Full-Attack Action(two kukri): +14/+14/+9/+9

Now that you can make multiple attacks of opportunity in a round, maximizing the ways you can get them will improve your per-round damage output significantly.  By this time, you and your party should be familiar with each other and comfortable in your roles.  If you generally find yourself adjacent to a friendly melee attacker, Opportunist gives you the ability to attack once out of turn for free when they do.  

15: Rogue (Knife Master) 15, +1/6 Rogue talent, base Hit Point range 39-137

            BAB: +11/+6/+1

AC: 19 (10+5 DEX+3 leaf armor), 22 with Combat Expertise, +5 against light blades, +8 for one round after sneak attacking

            Saves: +7/+15/+7

Feats: Blade Sense (+5), [15^th Level Feat] Greater Two-Weapon Fighting

            Sneak Attack: +8d4 / +8d8 with daggerlike weapons, 2 STR damage

Unenhanced Full-Attack Action(one kukri): +17/+12/+7

            Unenhanced Full-Attack Action(two kukri): +15/+15/+10/+10/+5/+5

This is the first possible level at which you can get Greater Two-Weapon Fighting.  Now you have your full six attacks (seven with haste).

16: Rogue (Knife Master) 16, +1/6 Rogue talent, base Hit Point range 41-146

            BAB: +12/+7/+2

AC: 20 (10+6 DEX+3 leaf armor), 23 with Combat Expertise, +5 against light blades, +8 for one round after sneak attacking

            Saves: +7/+17/+7

            Ability Score Increase: DEX +1 (22)

Feats: Hidden Blade (+8), Rogue Talent: Defensive Roll

Unenhanced Full-Attack Action(one kukri): +19/+14/+9

            Unenhanced Full-Attack Action(two kukri): +17/+17/+12/+12/+7/+7

Defensive Roll allows you to, once per day, attempt to make a reflex save against an attack that would bring you below 0 hit points to take half damage instead.

17: Rogue (Knife Master) 17, +1/6 Rogue talent, base Hit Point range 43-155

            BAB: +12/+7/+2

AC: 20 (10+6 DEX+3 leaf armor), 23 with Combat Expertise, +5 against light blades, +9 for one round after sneak attacking

Feats: [17^th Level Feat] Skill Focus: Bluff

            Sneak Attack: +9d4 / +9d8 with daggerlike weapons, 2 STR damage

Seventeen is a pretty quiet level.  Your BAB doesn’t improve, your saves don’t get better, and you only get one feat.  I recommend Skill Focus: Bluff for an impressive +6 bonus to your Bluff score.

18: Rogue (Knife Master) 18, +1/6 Rogue talent, base Hit Point range 45-164

            BAB: +13/+8/+3

AC: 20 (10+6 DEX+3 leaf armor), 23 with Combat Expertise, +6 against light blades, +9 for one round after sneak attacking

            Saves: +8/+18/+8

Feats: Hidden Blade (+9), Blade Sense (+6), Rogue Talent: Another Day, [Favored Class Bonus] Rogue Talent: Fast Gataway

Unenhanced Full-Attack Action(one kukri): +20/+15/+10

            Unenhanced Full-Attack Action(two kukri): +18/+18/+13/+13/+8/+8

This level marks your third and final human bonus Rogue Talent, and you’re taking Another Day to improve your survivability in combat situations.  At these higher levels, most rogue builds are glass cannons- you’re a little more resilient and with your huge damage potential, that extra round or two is hopefully enough to kill what’s killing you before it finishes.  Fast Getaway is meant to be paired with the Decoy Ring, which makes your character invisible and creates active mirror images when you withdraw from combat.

19: Rogue (Knife Master) 19, +1 Hit Point, base Hit Point range 47-173

            BAB: +14/+9/+4

AC: 20 (10+6 DEX+3 leaf armor), 23 with Combat Expertise, +6 against light blades, +10 for one round after sneak attacking

            Saves: +10/+18/+8

Feats: [19^th Level Feat] Great Fortitude

            Sneak Attack: +10d4 / +10d8 with daggerlike weapons, 2 STR damage

Unenhanced Full-Attack Action(one kukri): +21/+16/+11

            Unenhanced Full-Attack Action(two kukri): +19/+19/+14/+14/+9/+9

20: Rogue (Knife Master) 20, +1 Hit Point, base Hit Point range 49-182

            BAB: +15/+10/+5

            Saves: +10/+19/+8

Ability Score Increase: DEX +1 (23)

Feats: Hidden Blade (+10), Master Strike, Rogue Talent: Feint Expert

Sneak Attack: +10d4 / +10d8 with daggerlike weapons, 2 STR damage, sleep 1d4 hours / paralyzed 2d6 rounds / slain DC Fort 22

Unenhanced Full-Attack Action(one kukri): +22/+17/+12

            Unenhanced Full-Attack Action(two kukri): +20/+20/+15/+15/+10/+10

Feint Expert at level 20 allows you to reroll five feints per day.  The difference between a successful two-weapon feint full attack and a failed two-weapon feint full attack is a potential +50d8 damage, 10 STR and your choice of master strike effect.  It’s another re-roll feat hampered by the “before the results are revealed” clause though, so it’s mostly for bosses and powerful inquisitor-/paladin-/demon-like enemies against which you roll low.  To feint a Balor (CR 20) you need to beat a 50, which means against that particular enemy you’ll need at least an additional +7 modifier to succeed on a natural 20.

The rogue talent Face In The Crowd is useful if your party is normally within 30 feet of each other most of the time.  It gives a -2 penalty to opposing Sense Motive and Perception checks against your Bluff, Disguise, Sleight-Of-Hand and Stealth when within 30 feet of two or more non-hostile humanoids, which would include feinting in combat.  It depends on your DM and whether they agree that the non-hostile is in reference to you or if they feel that you can only use this talent outside of combat.

If you plan on using the substantial situational bonus provided by Hidden Blade, the rogue talent Underhanded adds a further +4 to weapon concealment and maximizes(!) your sneak attacks if done with a hidden weapon during a surprise round, probably killing an opponent outright if the conditions line up.  It’s a very good murderfeat for a stealthy Knife Master; however, the amount of times per day you can use Underhanded is limited by your Charisma modifier, so you’d need a Headband of Alluring Charisma.

Slow Reactions prevents attacks of opportunity from enemies struck by your sneak attack for one round, allowing a risk-free departure or providing safety for an adjacent allied caster.

Level 10+

Hamstring Strike is an advanced talent which allows you to use an attack to attempt to knock an enemy prone and unable to move(!) instead of dealing sneak attack damage with a Fortitude DC of 10+½ Rogue level+DEX which sounds good, but by the time you can take this, you’re likely doing enough damage to kill enemies who’d reliably fail that Fortitude save outright.

Unwitting Ally is an advanced talent situational to larger combats and requiring some clever positioning but which is well-suited for the high-Bluff Knife Master you are.  With it you can Bluff an enemy who would give you flanking against another enemy into appearing like a flanking partner, and if your DM considers the action a lie, your Mask Of Stony Demeanor grants a +10 on the Bluff check.

Of Particular Note

Creatures immune to sneak attack: oozes, elementals, incorporeal creatures (without the Ghost Touch weapon ability), swarms, proteans (50% chance to ignore precision damage) and enemies with the Light/Moderate/Heavy Fortification (25%/50%/75% chance to ignore precision and critical hits) armor special ability or the Fighter: Armor Master’s 9^th level Fortification feat.