It really depends on what you want:
Dex has more dmg from more Ap in vistani, a slightly higher assassinate dc and the option to take scion of Ethereal to trade 4 dc of assassinate vs more SAdmg.
Int has a better Dire Charge Dc from Kta and the possibility to get a high dc Crowdcontrol from magical traps and twist daunting Roar. It looses one feat for insightful reflexes and 8Ap for magical traps though and doesnt offer the opportunity to take the vistanicapstone, so its best to play int as a pure assassin. With the better control options Int should be better suited for soloplay.
damagewise a rog 18 mnk 2 build dex would most likely be the best choice.
Its a glasscannon build though and sacrifices some defense and utitlity like sneakspeed. with the possibility to take the capstone of vistani it is damagewise not necessary to stay pure for an assassin anymore. Vistani offers 5% combat speed and +10Mp for loosing 4Sa against a pure Rogue.
Glassknife
18/2 Rogue/Monk
Lawful Neutral Shadar-kai
Level Order
1. Rogue. . . . . .6. Rogue. . . . . 11. Rogue. . . . . 16. Rogue
2. Monk. . . . . . 7. Rogue . . . . .12. Rogue . . . . .17. Rogue
3. Rogue. . . . . .8. Rogue. . . . . 13. Rogue. . . . . 18. Rogue
4. Rogue. . . . . .9. Rogue. . . . . 14. Rogue. . . . . 19. Rogue
5. Rogue. . . . . 10. Rogue. . . . . 15. Monk. . . . . .20. Rogue
Stats
. . . . . . . .28pt . . 32pt. . .34pt . . 36pt. . .Tome. . .Level Up
. . . . . . . .---- . . ----. . .---- . . ----. . .---- . . --------
Strength. . . . .8. . . . 8 . . . .8. . . . 8 . . . +3 . . . 4: DEX
Dexterity . . . 18. . . .20 . . . 20. . . .20 . . . +6 . . . 8: DEX
Constitution. . 14. . . .14 . . . 14. . . .16 . . . +4 . . .12: DEX
Intelligence. . 14. . . .14 . . . 14. . . .14 . . . +5 . . .16: DEX
Wisdom. . . . . 10. . . . 8 . . . 10. . . .12 . . . +3 . . .20: DEX
Charisma. . . . 10. . . .10 . . . 10. . . . 6 . . . +3 . . .24: DEX
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28: DEX
Skills
. . . . . R. M .R .R .R .R .R .R .R .R .R .R .R .R .M. R. R. R. R. R
. . . . . 1. 2 .3 .4 .5 .6 .7 .8 .9 10 11 12 13 14 15 16 17 18 19 20
. . . . .------------------------------------------------------------
Concent . . .5. . . . . . . 1. 1. 1. 1. 1. 1. 1½ 1½ 4 . . ½. 1½ 1½ 1½ 23
Disable . 4. . .1 .1 .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 . . 1. 2. 1. 1. 1. 23
Open Lo . 4. . .1 .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 . . 2. 1. 1. 1. 1. 23
Search. . 4. . .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 . . 2. 1. 1. 1. 1. 23
Spot. . . 4. 1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1. 1. 1. 1. 1. 1. 23
Bluff . . 4. . .1 .1 .1 .2 .1 .1 .1 .1 .1 .1 .1 .1 . . 1. 2. 1. 1. 1. 23
Jump. . . 4. . .1 .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1. 1. 1. 1. 1. 1. 23
Hide. . . 4. . .1 .1 .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1. 1. 1. 1. 1. 1. 23
Move Si . 4. 1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1. 1. 1. 1. 1. 1. 23
UMD . . . 4. . .2 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 .1 . . 2. 1. 1. 1. 1. 23
Tumble. . 1. . . . . . . 1. 1. 1. 1. 1. 1. 1. . . . . . . . . . . . . .8
Balance . 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
. . . . .------------------------------------------------------------
. . . . .40. 7 11 11 11 11 12 12 12 12 12 12 12 12 .8 12 12 12 12 12
Feats
.1. . . . : Improved Feint
.2 Monk . : Two Weapon Fighting
.3. . . . : Two Weapon Defense
.6. . . . : Adept of Forms
.9. . . . : Improved Two Weapon Fighting
12. . . . : Improved Critical: Piercing
15. . . . : Master of Forms
15 Monk . : Precision
18. . . . : Greater Two Weapon Fighting
21 Epic . : Overwhelming Critical
24 Epic . : Improved Sneak Attack
26 Destiny: Perfect Two Weapon Fighting
27 Epic . : Grandmaster of Forms
28 Destiny: Elusive Target
29 Destiny: Dire Charge
30 Epic . : Blinding Speed
30 Legend : Scion of: Astral Plane
11 Rogue. : Improved Evasion
14 Rogue. : Opportunist
18 Rogue. : Slippery Mind
Enhancements (80 AP)
Vistani Knife Fighter (41 AP)
- Knife Expertise, Knife Juggler, Knife Specialist, One With Blades, Vistani Fortune, Knife Master
- Vistani Knife Training, Undead Hunter, Mist Stalker, Acrobatic II, Rapid Attack
- Vistani Knife Training, Bleeding Cuts, Mist Stalker, Weapon Versatility, Haste Boost
- Vistani Knife Training, Fan of Knives, Mist Stalker, Deadly Blades, Dexterity
- Vistani Knife Training, Celerity, Mist Stalker, Double Daggers, Dexterity
Assassin (35 AP)
- Knife in the Darkness, Dagger in the Back, Assassin's Trick, Nimbleness, Lethality
- Shiv I, Sneak Attack Training, Stealthy II
- Venomed Blades III, Sneak Attack Training, Damage Boost III
- Critical Mastery III, Sneak Attack Training, Dexterity
- Execute, Sneak Attack Training, Dexterity
- Assassinate, Measure the Foe I, Knife Specialization
Thief-Acrobat (3 AP)
- Staff Control
- Fast Movement
Henshin Mystic (1 AP)
Destiny
Twists of Fate (31 fate points)
- Symetric Strikes (Tier 4 Primal)
- Balanced Attacks (Tier 3 Primal)
- Rejuvenation Cocoon (Tier 1 Primal)
- Dance of Flowers (Tier 1 Flowers)
- Extra Action Boost (Tier 1 Dreadnought)
2 monk are for 10% mp from hensin, 2 feats >> grandmaster windstance 12%doublestrike and +4 dex, +4% doublestrike frome legendary feat (astral plane) for beeing centered, +1,5 w from twisting dance of flowers.
You can ditch the 10 mp from henshin for +1 MtF if u use it regulary or u could decide against movementspeed for max dmg to go 39 Ass and get the nice boost from deadly strikes.
Destiny is Shadowdancer or Dreadnaught, switch action boost twist to Stealthy if going Dreadnaugth
Dual defense feat helps with the low defenses and can be swaped for Sap or Tougness or even +2 wilsave
Same goes for elusive target switch it for holystrike, pierce dmg or first blood
Compared to Hassan build this build has +20% offhand strike, +2,5w basedmg, +26% doublestrike, +10% offhand doublestrike, + 20Mp, +5% combat speed loosing 5 Sa 2 Assassinate and deadly strikes dmgwise.
The main difference to a pure build with 23 Ap in vistani is the +16%doublestrike and 5% combat speed, +20Mp and +1,5w traded vs 4Sa, 2 dc Assassinate and deadlystrike
But u loose prr from leather armor some max dodge and utility like immune to slippery or imp defensive roll
With the possibility to splash the Assassin without loosing dmg by taking the vistani capstone, you have lots of possibilities to add some funstuff from splashes like Movementspeed from barb.
A pure Build still has the highest Assassinate dc. A rog 19 mnk 1 version of the above build would only be 1 behind though. -1 rog lvl, -3 capstone vs +1 vistanicap (+2 to all abilities), +2 from +4 dex from windstance.
hope this helped a bit and wasnt to detailed, had the glassknife in mind now for a while and it seemed like good opportunity to outline it.
Feel free to ask