Hey everyone, first post here.
This is my assassin build that I use in PvE, hopefully someone will find use for it:

16 Dagger
10 Tactics
8 Critical

Mark of Instability
Black Mantis Strike (It may be Thrust)
Death Blossom
Falling Spider
Blades of Steel (optional -- if you need res sig replace this skill)
Flashing Blades
Watch Yourself!
Healing Signet
(res sig if needed)

The idea is to keep FB and WY! up constantly - you can tank against melee all day if you have a decent monk. Don't try to take on 5 elementalists 5 mesmers and 5 necros though!

not to be mean...but an assassin isnt a tank, thats why they have shadow stepping skills and only 70 armor....

Well they aren't MEANT to be tanks, but I can solo warriors with this build. Nightstalkers armor (+15 armor while attacking) and Watch Yourself! (+20 armor) 95 armor against physical

My assassin also has 490 health. I can tank. I did not say I can take nukes and hexs all day.

I'll show you if you want.

I believe if you won't to even try and tank to use a crit or shadow build. Crit builds having Crit Def which I only use if a warrior makes the mistake of coming after me.

Shadow builds also have a move that last for 20 secs, but I forget what its called.