Well, once you reach a certain point in the game, Professor Ambrose will call you and give you a quest to defeat Foulgaze. After that you battle Lord Nightshade.
you have to be lvl. 12
Get a banshee from lord nightshade
You must first finish all 3 streets which are Triton Avenue, Cyclops Lane and Firecat Alley and after you finish them, you will get the badge, three streets saviour.After you get the badge, Headmaster Ambrose will call you and tell you that the time has come for you to defeat Lord Nightshade.
You will need to defeat lord Nightshade in haunted cave, after you finish the main quests in fire cat alley, Triton Avenue, and Cyclops Lane
he is in the tower in the hunted cave he is Lord Nightshade
fight lord nightshade
you first must beat lord nightshade in wizard city and then go back to ambrose who will give ya a spiral key to krokotopia.and so on with other worlds you complete enough quests to make it to the next. the only exception is grizzleheim really.
Beat Lord Nightshade or ask a friend who can go to Nightside to go in there. Then teleport to him or her.
You compleate all of the main storyline quests in Wizard City. That means Unicorn Way, Triton Avenue, Cyclops Lane, Firecat Alley, and defeating Lord Nightshade. To see the quest line word for word, go to Wizard101 Central WIKI and click in quest trees "Wizard City"
Defeat all the quests up to about level 15 and you can face him.
You have to defeat lord nightshade in stormdrain tower. If you don't have access to stormdrain tower, ask someone else to go inside for you. That's what i did.
Really to get into the castle you have to be on a quest or teleport to a friend in the battle with lord Nightshade