I believe that complexity is challenging to master and will ultimately lead to less than optimal results. Hence, I have tried to create a build and a rotation based on as few rules and as many macros as possible (i.e. the least possible complexity in playing) that still delivers an acceptable damage output.
A different assignment of points together with a keen use of timers and abilities may lead to higher damage output in a perfect setting with a perfect player, but many of us (myself definitely included) will never achieve perfection. - Hence, this build.
Please comment on potential improvements / further reduction of complexity.

The build:
http://rift.zam.com/en/stc.html?t=1M...R.VbdN0o.V0xMh

The buffs:
Hellfire Blades
Lethal Poison
Combat Pose

The macros & buttons:
Intro Macro (“IM”) to be included in the beginning of most macros:
# cast poison malice
# cast reprisal
# cast blade tempo
# cast side steps


Stealthed, Button 1:
“IM”
# cast Jagged Strike

Stealthed, Button 2:
“IM”
# cast Assasinate
# cast Dark Malady

Stealthed, Button 5:
Expose Weakness



Unstealthed Button 1:
“IM”
# cast Puncture
# Cast Impale


Unstealthed Button 2:
“IM”
# cast Dusk Strike
# cast Precision Strike
# cast Quick Strike
# cast Keen Strike
# cast Fiery Spike

Unstealthed Button 3:
“IM”
# cast Deadly Strike

Unstealthed Button 4:
“IM”
# cast Foul Play
# cast Weapon Barrage
# cast Blinding Powder

Unstealthed Button 5:
# cast Slip Away

The Rotation:
Abbreviations: "SBX" = Stealthed Button number X / "UBX" = Unstealthed Button number X

Attack preparation: SB5
-> Simple rule A: Before a battle, press “5” once (or how many times you want …)

Actual Attack: SB1 (Jagged Strike, 3 combo) UB1 (Puncture, 2 combo), UB1 (Impale)
-> Simple rule B: To start a battle, press “1” 3 times

UB2 (Dusk Strike, 2 combo), UB2 (Keen Strike, 1 combo), UB2 (Precision Strike, 2 combo), UB3 (Deadly Strike)
-> Simple rule C: Keep pressing “2” until you have 5 combo points (initially 3 times), then press “3” once and begin anew

-> Simple rule D: If you see the opponent cast something hit “4”

-> Simple rule E: If you ever think “oh ****” hit “5” (as much as you want). Continue with rule A when you feel better.

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Now the clever guys will find one snag in the above rules for sure: “Simple rule C” may cause a problem if the opponent flees, as the combo points will not go down, lacking a ranged finisher.
So, to make these rules absolutely foolproof, here is an alternative build, but I suspect that damage will be lower, lacking the passive permanent damage increases from the NightBlade soul. (I should add, that I have not yet used Dancing Steel, so this may need to be moved in the macro - please comment).

The build:
http://rift.zam.com/en/stc.html?t=1M....VbdA0sRohbz.z

The buffs:
Virulent Posion
Lethal Poison
Combat Preparation

The macros & buttons:
Intro Macro (“IM”) to be included in the beginning of most macros:
# cast poison malice
# cast reprisal
# cast blade tempo
# cast double coup
# cast side steps


Stealthed, Button 1:
“IM”
# cast Jagged Strike

Stealthed, Button 2:
“IM”
# cast Assasinate
# cast Jagged Strike

Stealthed, Button 5:
Expose Weakness



Unstealthed Button 1:
“IM”
# cast Puncture
# cast Impale
# cast Headshot

Unstealthed Button 2:
“IM”
# cast Dancing Steel
# cast Precision Strike
# cast Quick Strike
# cast Keen Strike
# cast Flash of Steel
# cast Quick Shot

Unstealthed Button 3:
“IM”
# cast Deadly Strike
# cast Headshot

Unstealthed Button 4:
“IM”
# cast Foul Play
# cast Weapon Barrage
# cast Blinding Powder

Unstealthed Button 5:
# cast Slip Away

The Rotation:
Abbreviations: "SBX" = Stealthed Button number X / "UBX" = Unstealthed Button number X

Attack preparation: SB5
-> Simple rule A: Before a battle, press “5” once (or how many times you want …)

Actual Attack:
SB1 (Jagged Strike, 3 combo) UB1 (Puncture, 2 combo), UB1 (Impale)
-> Simple rule B: To start a battle, press “1” 3 times

UB2 (Keen Strike, 1 combo), UB2 (Precision Strike, 2 combo), UB2 (Keen Strike, 1 combo), UB2 (Quick Strike, 1 combo), UB3 (Deadly Strike)
-> Simple rule C: Keep pressing “2” until you have 5 combo points (initially 4 times), then press “3” once and begin anew

-> Simple rule D: If you see the opponent cast something hit “4”

-> Simple rule E: If you ever think “oh ****” hit “5” (as much as you want). Continue with rule A when you feel better.