Instructions
Fight against other players or against non-playable characters to increase your Defence and general fighting skills until you either have a combined Attack and Strength level of 130 or when the individual level of either one of those skills is at least 99. By fighting, you will also incidentally increase your Defence skill. Reaching the aforementioned skill levels will allow you to enter the Warriors' Guild.
Travel to the Warriors' Guild, which is in Bulthorpe. Enter the building.
Speak to the dwarf and enter the Catapult Room. Successfully block the catapult's ammunition with your shield to receive 10 Defence points. You can repeat this activity as many times as you want.