Talk to Shadeen after finishing the Poison Apple quest. Say “Mission”, “Yes” and she will give a scroll of evil deed. For completing this quest you will need help from a friend. Give your friend the scroll of evil deed and he can speak to Doremas (located west from Silversky fountain). Say to Doremas “Scroll of Evil Deed” and he says that you must open the castle safe. To find the combination, your friend, must say “Combination” to the following NPCs: Rondy (near Silversky fields), Geram (the drunk fellow at Silversky tavern) and Talon Irongaze (the banker, near the Silversky safe).
Rondy will ask you to play a game with numbers (higher-lower from 1 to 50) until you find the number. Any wrong numbers cost you 1000 gold pieces. Continue until you find the 1st number of the combination. (Keyword: Combination“, “Guess XX” (XX=number from 1 to 50)).
Geram will ask for a gold coin. Say “Yes” then “Combination” and he will ask for a Empty Bear Mug. You can find the Mug from the Cape of Fire Resistance quest or just buy one from the innkeeper for 10 gold pieces. Then say again “Yes”, “Combination”, “Yes” to Geram and he will give you the 2nd number of the combination.
Now go to Talon Irongaze and say “Combination”. He will ask for a Tiger's tooth. Go to Lighthaven and find a NPC called Siegfried (Weapon dealer, north from temple). Say “Tooth”, “Part”, “Yes” and you will buy a “dragon's tooth” for 200 gold pieces. Go back to Talon Irongaze and say “Combination”, “Yes”. He will say that you don't have the tooth. Head to Nafuhr Bloodhammer (Silversky armor dealer). Say “Dragon Tooth” and he will tell you that the tooth is fake. Go back to Siegfried and say “Dragon Tooth”, “Dragon Tooth”, “Yes” and he will admit that the tooth is fake. He will change it with a Tiger Tooth. Back to Talon Irongaze and say “Combination”, “Yes” and he will give you the 3rd number of the combination.
Now your friend must go to open the safe and YOU must go and stand beside Menark (at the library of the castle). Once he open the safe, he will page you done (he will receive 10000 experience points and 3000-4500 gold pieces). Once your friend pages you, click on Menark and say “Chronicles of Doom”. He will ask you if you threaten him. Say “Yes” and he will shout for the Guards. Since the guards are distracted trying to catch your friend who opened the safe, they will not come to his help, and he will give you the Chronicles of Doom. Head back to Shadeen and say “Yes” (for karma up) or “No” (for karma down) and then “Reward”. You will be rewarded with 5000 experience points and a Silver Feather, used in the evil path to Stoneheim.