A little idea I've been toying with, figured I'd leave you guys with it as I head off to bed. Sorry I didn't post true descriptions, but I'm sure you can figure out why.
Return- Warps to target ally. All enemies around you pre-warp are crippled.
Death's Charge- Warp to target enemy. If he's got more health than you, you get some.
I've been wanting to make use of the Shadow Step skills (Espically Death's Charge and Return). In this idea, if there are three people present, two are assassins. One uses Death's Charge to rush an enemy behind the front lines, and unloads on them. As soon as their combo is done (teamspeak would help for this...) the other assassin smashes Return and warps to them, unloading their combo now on the target. Right after the tag assassin warps in, the other one could Recall out to the third non-assassin ally.
Keep in mind I'm going of GWG's descriptions, which are at times outdated. Thoughts?
(This would be best suited to 4v4, most likely)
Tag Team Assassins
MysticPain
Farthest Point
I had the same idea in mind. What you could do is use "Shadow Refugee" whenever you approach your target, since it only lasts 4 seconds and you wont be in that spot very long. Also use "Caltrops" to cripple everyone around you so, your tag team assasin could easily finish the job if needed.