The Defence cape is a Cape of Accomplishment that players can purchase only when they've reached level 99 in the Defence skill. It can be bought from Harlan, the Defence tutor, for 99,000 coins close to the Lumbridge general store.
Like all skill capes, the Defence cape gives +9 to all defensive stats, and also a +4 bonus to prayer if it is trimmed, which requires a separate skill at level 99. The cape is automatically trimmed if this condition is met.
When the defence cape is equipped, players can enable the cape to act as a ring of life. This option is toggle-able, and can be enabled/disabled by the player at any given time. When the effect occurs, the wearer will receive the message "Your cape saves you.".
As of 1 September 2018, there are 76,633 current members that have achieved level 99 in Defence.