Magic whistle

The magic whistle is obtained from the top room in Draynor manor while the player has a holy table napkin in their inventory. Two whistles spawn at once, one for you and one which must be given to Percival during the Holy grail quest.

Blowing the magic whistle while standing where the stone faces point (under the tower to the north-west of brimhaven) allows for players to access the black gardens.