So, after much agonising, i put forward the hypothesis that the most effective utilisation of the new ninja-spy PrE is the following. Originally i thought multiclassing would be the best use for this PrE but it just isn't true. Goals: dual wielding shortswords, stealth capable, effective combat DCs.
Drow pure dark path monk ninja-spy (LN)
str 14 (+2 tome)
dex 16 (+4 level ups)
con 13 (+1 level up and +2 tome)
int 12 (+1 tome)
wis 14 (+2 tome)
cha 10
A TR character and/or having +3 or +4 tomes to attain 16 base str and con and 13 int to qualify for master elemental enhancements and CE would be ideal for this build. Like all monks this build is MAD.
skills: max concentration and UMD. Split leftover between move silently (15), spot (15), balance (12), tumble (1)
(hide isn't needed as unlimited invisibility, jump is sacrificed. Spot is to see hidden enemies while stealthed)
feats:
1: TWF
1: toughness
2: weapon finesse
3: dodge
6: combat expertise
6: resilience (swap for precision at 16)
6: ninja-spy bonus: shortswords as monk weapons
9: ITWF
12: power attack
12: ninja-spy bonus: improved critical: shortswords
15: GTWF
18: skill focus: UMD (or weapon focus: piercing)
Drow is interchangeable with 32 point halfling however, another halfling monk is boring.
Enhancements are tight. I took 14 starting str and con to qualify for master elemental paths to qualify for Void Strike IV (wind stance IV vorpal hits).
Feats are pretty straight forward, resilience/precision and skill focus: UMD are optional. Personally, I like to be able to go through elite traps all through the game playing the clever monkey game. Precision is for epic content. Additionally, being able to voluntarily lower your damage to boost ki generation is very effective if soloing or the rest of the party is cooperative (ie doesn't kill the enemy your slowing beating to death for Ki).
2 Drow Melee attack I
2 Drow melee damage I
2 Elven Dexterity I (no room to take more)
1 Racial Toughness I
6 Ninja-spy II
10 Grandmaster of storms
18 Master of Stone, Bonfires and Sea
10 Void Strike IV
1 Fists of iron
1 Unbalancing Strike
3 Way of the elegant crane II (no room to take more)
1 Fists of Darkness
4 Touch of Death
2 Static Charge
2 Porous Soul
2 Winter's Touch
2 All-consuming Flame
3 Monk Balance II
3 Monk Jump II
2 Monk Wisdom I (no room to take more)
Monk Improved Recovery I (no room to take)
2 Monk Serenity
1 Monk Concentration I (filler)
80
The racial enhancements will be most useful to have leveling up but the level 20 distribution is not that great. Possible (though difficult) to redistribute enhancements to max dexterity and drow weapon attack II to be able to hit epic content better.