How to Solve
To start Tornaum Castle go to the top right room in the castle and grab the club from the bookshelf. Then proceed to the middle of the castle and go down the stairs. When in the jail cell area apply plants until you find the lever. Then proceed to the open cell and apply the lever inside. This will open up three cells that each have a Random Dungeon (RD) in them. Proceed to the bottom each RD until you find the one that has a sign reading "Those who have committed crimes against the World of Wyvern are housed here."
The sewer you want will have golems inside of it instead of Evil Eyes or Minotaurs like the wrong RDs have. When you've made it to the right dungeon proceed to the right side of the map. You will have to fight Undines if you wish to go around the Lichs and Shoggoths. On the other side of the cells unlock (or smash) the door to the left and enter the dragon cells. There will be a blue key inside one of the cells. Use the blue key on the door to the right that is guarded by Iron Golems and type unlock in the command prompt to open the door. After opening the door rush through the underwater area (you don't need to kill anything in here) and find the giant. Give the club from the king's room to the giant and you will receive a big club. Exit through the top of the giants room and enter cave.
Inside the cave you will see a lot of breakable walls and smash your way around until you find a stone giant. When you find the stone giant give the big club to him and you will receive a scepter. Exit the smashing cave and proceed to the bottom of the grassy area and you will return to Tornaum Castle.
Give the Scepter to the King and you will complete the quest.
Things to keep in mind!
◘Bring a light source!◘
◘Bring X-Ray Vision (helmet)!◘
◘Bring something to smash blocks!◘
◘Bring fire and cold resistance!◘
◘Bring lock-picks, or a means to open doors!◘
◘Make sure to grab the club before going in the RDs!◘
fly spell and water breathing spells/potion/scroll