Sorry, I haven't looked into Nightfall much, but how many character slots will be avaliable? Will it increase to 7 or 8+, or will it stay at 6 slots? Answers will be appreciated
If you have just NF: 4 slots.
If you have Prophecies + Factions currently linked together and have 6 slots and add your Nightfall key to them: 4 slots (P) + 2 slots (F) + 2 slots (NF) = 8 slots
If you have added the Pre-release Bonus Pack key to your current P+F account and then add a NF key as well: 4+2+2+1=9
What if you bought Prophecies, then addded Factions, the bought 2 character slots, then bought the Pre-release pack, then bought Nightfall?
4+2+2+2+1=11
What if you bought Prophecies, then addded Factions, the bought 2 character slots, then bought the Pre-release pack, then bought Nightfall?
4+2+2+2+1=11
Then you will indeed end up having 11 characters slots. And if you buy two additional character slots after the release of Nightfall, you will have 13 slots...