A bit lost now: Assassin Ranger -> A/Dervish?

Hi folks.

A few months back, I made a post asking about making a scythe-wielding class that was a little more survivable, and someone suggested I make an Assassin Ranger, then turn him into Assassin Dervish upon finishing the Factions Campaign.

My issue is that I have no idea how viable that is anymore, and I would like very much to still use my Assassin and make it a A/dervish after Factions.

I was hoping someone could give me more information on what I might be able to do in this case? I'd like to get some direction to make my future Assassin/Dervish strong enough for PVE without getting too technical with all the terminology as I suck at that.

Thanks for your time.

with the dervish update dervish primaries work best for scythes imo.
their crit dmg was nerfed so running assassin primary has lost its thunder i'm afraid :/

http://www.gwpvx.com/Build:A/D_PvE_Scythe_Sin

Vow of Strength also works.