Too much like d2, I think it should be more like the ttk mission, starting with a skirmish, perhaps a few darkness ships, and then ending with a climactic battle against the darkness where you go from ship to ship disabling the shields, and then you fight a good final boss that is very challenging, and it ends with the darkness mothership (aka anti traveler) being crippled, and then there is the raid in which you destroy the anti traveler. (The ending could also be one where you go inside the traveler to defend it)