Large door (Castle Wars) - OSRS Wiki

A pair of large doors are located within the outer wall of each team's castle inside of the arena where the Castle Wars minigame takes place. The double doors are one of the two main passages through the castle walls, the other being the lockable small door (both of which can be bypassed by either scaling the battlements or travelling through the underground tunnels).

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Pretty solid advice for people who want to try out Castle Wars : r/2007scape

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