QuickStrike
Assassin / Ranger
PvE/PvP (untested in GvG atm)
Catagory: Surgical Supportor (Secondary Melee? Trying to sound dramatic here..

)
Skill Set
Shadow of Haste (10e, 30 recharge)
Ususpecting Strike (10e, 4 recharge)
Fox Fangs (5e, 8 recharge)
Twisting Fangs (10e, 15 recharge)
Shadow Refuge (5e, 1 cast, 8 recharge)
Way of Perfection (5e, 1 cast, 30 recharge)
Apply Poison (15e, 2 cast, 12 recharge)
Res Sig
Attributes
Wilderness Survival 1
Dagger 10+1+3
Shadow Arts 10+1
Critical Strikse 11+1
Armor
Armor (70AL)
Bladed Mask (+1 dagger)
Vanguard's Guise (reduce blind)
Saboteur's Gloves (reduce bleed)
Shrounded Leggings (+2e)
Shrouded Shoes (+1e)
Summary
Alright, the basic plan is get in, drop a good amount of damage and conditions and then vanish. Simple enough. I focus on the casters, typically monks and mesmers.
You have enough time to cast Apply Poison, spend a few seconds selecting a target, then hit Shadow of Haste (note, you want to be about 2/3 of a compas distance away), finally charge in and hit your combos. If done right, a second or two after you drop your combo you'll teleport back across the screen way far away from the action. 75% of the time this is enough to kill a caster, when its not, it draws the monks attention away from front line warriors.
The armor will help with conditions, but Shadow Refuge will give you a quick recharge on health if you need it.
While waiting for your combo to recharge, or if you've taken out all caster targets, I tend to pop Way of Perfection and hit the remaining targets without Shadow of Haste. Just be careful here, as you might start falling into the "tank" mentality.
Notes & Concerns
The #1 thing about this build is patience. You are not a tank, don't act like a tank. Your job is to pick a target (typically I go Rit > Mo > Mes > Ele > Ranger > Wa or A) and unleash your combo so he is removed from combat or hurt serious enough to distract monks from front line allies.
Eneregy Management:
I hardly run out of energy. Between critical strikes and 4 pips of e-gen as you close in on your target, I have plenty. After you cast your first combo and you've returned to your starting point, spend a few seconds selecting a new target and allowing your energy to rebuild. You are not a DPS melee warrior, you don't need to be attacking every second. Your strength is in a fast flury of damage. It is better to spend a few seconds waiting for the right moment, than to waste energy and perhaps your life by charging in too early.
Weakness:
The same weakness applies here that applies to any melee-based build. Blind. Blind will make you curse, but with the 20% reduction you're typically fine before your Shadow of Haste wears off. Also, since you are running in after your warriors have engaged front lines, typically Blind has already been used on them. If the character is saving it specifically for you, they are distracting themselves from their other duties, which works to your groups advantage in the long run.
Stance Defenses are a little bit of a pain as well, but not a true weakness. If someone pops a stance (lightning reflexes being my current hatred) just go on to someone else. If they are applying it before your combo, then you still have your full combo to use on someone else. If they try to do it midway through your combo, you typically beat them.
Original Discussion Thread
Credit
Does-it-Matter and Nesto