As far as I know, I've completed all of the Wizard City quests, but have not been able to access Nightshade. This may be a dumb question to ask, but where exactly is Nightshade located at and what quest or quests must I complete before I am able to access that area
When you finish the three streets off Olde Town; you will get a quest from the Headmaster to go get a key from the tower in Olde Town. That quest will eventually get you to find the door under the waterfall....and then the key to travel the spiral to Krokotopia!
Cynical is right. If you do enough Quests, the Headmaster will give a Quest about the Library Achives. One Quest later, You'll get a Quest to defeat a red ghost(???!!!)named Foulgaze. Quest after, you have to defeat a Grim Reaper guy named Lord Nightshade. When you(eventually)defeat him, a speech bubble will pop up saying you found a Skeleton key! "Report" back to the Heaadmaster and you will give him the Skeleton key. Quest after, He gives the Key back and tells you to check out the door under the waterfall next to "Rainbow Bridge"(it's in the Commons!). When you reach the door under the waterfall You'll be in Nightside!
P.S If your havin trouble with the Library Dues quest, the Death book will be in Lord Nightshade's Tower
P.P.S I called the place Nightside because that's the place's name!