Create this party

[Kafana]

https://www.youtube.com/watch?v=xzCEdSKMkdU

Alright, so based on what you can see here how what would you say the appropriate classes would be for these 4 assassins? Make use of obscuring mist instead of the smoke bomb.

Also, feel free to use your imagination to fill in the blanks that this trailer doesn't show, as nobody really uses all their class abilities in one set of encounters, even if it's a long set.

[prufock]

Their abilities seem pretty homogeneous, really, apart from different weapons and slightly different fighting styles. Swordsages all.

[Xerlith]

Factotum3/Urban Ranger 2/Exoticist Hit-And-Run Fighter1/Swordsage14

Human
1 Urban Ranger 1: Dodge, Weapon Finesse
2 Fighter 1: Mobility
3 Factotum 1: Roofwalker
4 Factotum 2
5 Factotum 3
6 Urban Ranger 2: Roof-Jumper, Two-Weapon Fighting (Ranger style).

Exoticist for Gnomish Quickrazor. Make the Quickrazor Wand-Chamber'd and put [your favourite blasting spell] in there.

Max Balance, Jump and Tumble, put some ranks into Iaijutsu Focus, Hide and (less) Move Silently.
EDIT: AND CLIMB. How did I forget about Climb...

Grab Craven at 9th level, you don't really need Shadow Blade with Iaijutsu+Sneak Attacks.

Pump Dexterity and Int.

Spice with Setting Sun and Tiger Claw maneuvers, sprinkling with occasional Shadow Hand. Grab Sapphire Nightmare Blade to flatfoot in combat. Done.

What you get: Mad Initiative (Dex mod+Int mod +2 Hit and run + Swordsage Quick To Act).
Falling on people for more damage.
Falling on things for less damage.
Hidden Blade.
Hidden Pistol (Oh come on, that Wand Chamber totally does it)
Coolness Factor
Differentiate between the guys with moving some maneuvers around. That's it.

[torrasque666]

Only problem with your build Xerlith, is that Hit-And-Run Fighter(from Drown of the Underdark, IIRC?) is a Drow racial substitution level. If I'm remembering the variant correctly.

[Xerlith]

Actually it is just from that book. Nowhere it states it can be taken only by drow. I read it over a few days ago because I'm using an almost identical (Warblade instead of Ranger) build in my current game.

[Drackstin]

i would say, Barbarian for the 2 handed axe, gunslinger for the gunner, alchemist for the guy with the bombs. and the main guy ether a rouge or slayer. sorry for pathfinder but it fits better.

[Extra Anchovies]

One of them should have a PsyWar dip for Up the Walls and other parkour shenanigans.

[Drackstin]

you can get those traits from skill tricks in complete scoundrel. so no reason to dip, but i think all should have 3 levels of slayer for SA and study target.

[weckar]

I agree with Extra Anchovies to a point. In universe, many of the Elder Assassins aren't full-blood humans. So: Elan. Gives the psionic feat goodness without the dip.

[Extra Anchovies]

I agree with Extra Anchovies to a point. In universe, many of the Elder Assassins aren't full-blood humans. So: Elan. Gives the psionic feat goodness without the dip.

And the whole ancient-secret-society fluff fits pretty well, too! Nice suggestion.

[BaronDoctor]

This looks like a job for the old Weekly Optimization Showcase. Vary things as you like, but this seems a good place to start. http://community.wizards.com/forum/previous-editions-character-optimization/threads/4106141