Factions and Nightfall Question

If I buy both expansions can I make a Dervish/Assasin in Nightfall straight away?

You don't need Factions to make a D/A.

You only need Nightfall to make a D/A, you don't need factions.

pug_ster is so wrong it's not funny. You need to have factions if you want to make anything that is /A. That said, since assassins are not a part of the nightfall world so far as createable character classes go, you'll have to wait atleast till you get to the Sunspear Sanctuary which is where you can change your secondary, and you may have to actually take your dervish into Factions and get to Senji's corner, which is the equivalent location in Factions. I'm not sure which of the two, because I haven't actually tried to change my Dervish to /A in the command post.

Dargon is correct, you need the Factions expansion in order to make a player character with an assassin secondary. You can unlock the sin secondary as soon as you have the profession changer npc in the Sunspear Sanctuary. It's not necessary to go to Senji's Corner to change any Nightfall character to /A or /Rt. However, you can make your heroes into /A or /Rt without Factions, but you won't be able to use the Factions only skills for those two clases.

r u kidding me??? that is like saying "u dont need peanut butter to make a peanut butter sandwich..."