Not sure whether this is still an issue at this point, but I have read that Assassinate dc's at major bosses. If this cannot be fixed, can someone at least tell me what bosses it dc's at, so that I know not to use it there. Also, if possible, what bossing skills do Shadowers use instead of Assassinate?
This is still an issue, and I do hope it gets fixed soon. Other than Assassinate, you need to rely on Smokescreen and Meso Explosion. Being able to drop tons of bags during a boss fight will give you the most DPS, I think. I have been doing that with my Shadower and it works well, although I'm sure Assassinate would be much stronger and easier to use.