Requirements: For this quest you will need to have 13 Quest Points. During the quest you will need an Iron Chainbody and Bronze Med Helm. You must also be able to defend against level 33 Black Knights.
Guide Map-
Secret Sabotage-
To start Black Knights' Fortress, speak to Amik Varze on the third floor of the west side of Falador Castle (As shown on the guide map). Tell him that you seek a quest and then that you laugh in the face of danger. He will tell you that the Black Knights have been threatening to invade and claim to have a secret weapon. You will need to infiltrate their fortress and sabotage the weapon. Tell him you will do your best and he will hand you a Dossier which when read will tell you what to do and then explode in a puff of smoke. Now you will need to equip the Bronze Med Helm and Iron Chainbody (it doesn't matter what you have equipped in the other spots) then head up to the Monastery marked on the map, grab a cabbage or two from the garden, and then head to the Fortress.
Navigating the Fortress-
Head through the front door, and then push the wall directly North of it to discover a hidden door. Climb up the ladder inside and then climb to the 3rd floor. Now climb down the ladder directly to the Southeast and go through the door to the East. Climb up the ladder inside that room, and then climb down the ladder that’s right next to the one you just climbed. Head through that rooms door and then climb down the ladder to the West. Now you will be in a small empty room, on the South East wall, click on it to listen in on a conversation. A witch will mention an invincibility potion, the last ingredient she needs is a cabbage from Draynor Manor, any other cabbage would ruin the potion.
Just Dropping In-
Now head back through the fortress to the entrance, and this time go through the door to the East of the entrance. The guard will warn you that its dangerous, tell him your going in anyway. Once you are in, quickly climb up the ladder at the North end of the room. Head to the Southeast end of this area and search the southern wall to find another hidden door. Now you will need to use (not eat!) the cabbage on the hole in floor. A cut scene will follow showing the cabbage falling in and ruining the potion. Now that your work is complete, head back to Amik Varze to complete the quest!
