After much deliberations. I think I've come up with a Sensei build. Ladies and Gentlemen. I give to you. The Wonder Punch!
This build is all about maximizing Vital Strike to its full potential; in order to deal the most amount of damage all in one singular punch! However, as you may have noticed. Why Vital Strike? In any other condition I would not recommend vital strike; this is because it cancels out flurry of blows. It's also sub optimal. Unarmed doesn't do enough damage to even justify investing the feats into it. However, since sensei doesn't get access to flurry of blows, you might as well build around that. (I am aware that there is a bug where the class still gets flurry of blows. I won't be exploiting that. Because it might get fixed in the future.)
Specifications of the build:
Race: Human
Class: 16 Sensei /4 Fighter
Alignment: Lawful Neutral or Lawful Evil.
Stats:
STR 18
DEX 14
CON 11
INT 7
WIS 18
CHA 7
Class/Feat Progression:
Level 1 - Sensei - Feats: Power Attack, Weapon Focus(Unarmed Strike), Deflect Arrows (Deflect Arrows is chosen because it's more optimal for the prologue. There are multiple archers in the prologue area. AC can easily be buffed with potions and spells. But being able to completely negate ranged users, is invaluable.) - Skills: Perception, Mobility.
Level 2 - Sensei - Skills: Perception, Mobility.
Level 3 - Sensei(It's very important to get three levels into monk as soon as you can. The reason being is due to KI Strike. The first KI Strike allows unarmed to be treated as magic for the purpose of bypassing Damage Reduction. Which is very important for unarmed users. Once you get three levels into monk, you can then start to multi class at level 4, if you wish.) - Feats: Dragon Style - Skills: Perception, Mobility.
Level 4 + 1 CON - Fighter - Feats: Dodge(Dodge is chosen late because of several reasons 1)Sensei doesn't get an additional feat at level two. 2)Dragon Style is more important in order to increase unarmed damage) - Skills: Perception, Mobility.
Level 5 - Fighter - Feats: Improved Initiative, Outflank (It should go without saying that fellow companions need to have Outflank. Either by level 5 or around level 6-8. You also need someone to be proficient in a high critical weapon in order to provoke Attack of Opportunities) - Skills: Perception, Mobility.
Level 6 - Sensei(You can go fighter or monk here. I like going monk for the KI Powers.) - KI Power: Barkskin - Skills: Perception, Mobility.
Level 7 - Fighter - Feats: Dragon Ferocity - Skills: Perception, Mobility.
Level 8 + 1 STR - Fighter - Feats: Vital Strike - Skills: Perception, Mobility.
Level 9 - Sensei - Feats: Weapon Specialization(Unarmed) - Style Strike: Shattering Punch(This won't work with this build, because it requires flurry of blows. At least that's what it says. Maybe some Pathfinder expert can clue me on the interaction on style strike. As for the in game interpretation, some of the style strikes don't even work. But none of it matters, since Sensei doesn't get flurry.) - Skills: Perception, Mobility.
Level 10 - Sensei - KI Power: True Strike - Skills: Perception, Mobility.
Level 11 - Sensei - Feats: Improved Vital Strike - Skills: Perception, Mobility.
Level 12 + 1 STR - Sensei - KI Powers: Abundant Step - Skills: Perception, Mobility.
Level 13 - Sensei - Feats: Improved Critical(Unarmed) - Style Strike: Hammerblow - Skills: Perception, Mobility.
Level 14 - Sensei - KI Powers: Restoration - Skills: Perception, Mobility.
Level 15 - Sensei - Feats: Critical Focus - Skills Perception, Mobility.
Level 16 + 1 STR - Sensei - KI Power: Diamond Body - Skills: Perception, Mobility.
Level 17 - Sensei - Feats: Greater Vital Strike - Style Strike: Defensive Spin - Skills: Perception, Mobility.
Level 18 - Sensei - KI Power: Diamond Soul - Skills: Perception, Mobility.
Level 19 - Sensei - Skills: Perception, Mobility.
Level 20 + 1 STR - Sensei - Feats: Shake it Off - KI Power: (Pick whichever one you fancy. We already got the best ones) - Skills: Perception, Mobility.
Fun fact, insightful strike will get overrided if your strength bonus is higher than your WIS stat. For example:
Screenshots of the build in action:
Level 1 to level 5:
Mid level:
High level:
The build was okay. One punching shit was amusing. All in all, I had fun with it. Thanks to Desiderius. If it weren't for him, I'd have never tried the class. Glad I gave it a go, and had fun with it.