You may use up to 2 Detachments (as defined in the Warhammer 40,000 Rulebook) to create your army. These may include unique Codex detachments which themselves are comprised of multiple subcomponents (i.e. the Decurion Detachment found in Codex: Necrons). You must otherwise follow all relevant rules for Battle Forged Army Construction, including use of a Warlord and Primary Detachment (which may not be an Allied Detachment). There are no restrictions on selection of the same Detachment twice (e.g., a Combined Arms Detachment).
The missions can be found here: http://www.novaopen.com/wp-content/uploads/2015-40K-GT-Invitational-Draft-Primer.pdf
And the Draft FAQ can be found here: http://www.novaopen.com/wp-content/uploads/2015-NOVA-Open-Warhammer-40K-GT-Draft-FAQ.pdf
Just as an FYI our MAX is 32 players. So if you want to play you should really call up the store and sign up. Please arrive between 10 am and 10:30. Round 1 will start around 10:45am. No need to sign up though it is preferred (and if we reach max and you're not signed up there's nothing I can do!). You can call the store at 703-466-0460 or visit their website www.huzzahhobbies.com for location / number. $15 gets you in and we feed you lunch! Also this is a cash only event. So please hit up that ATM before you get there as the closest one is a few miles down 7.
I'll see you guys there! Please let me know if you have any questions!