True skill mastery

True skill mastery is an achievement greater than skill mastery, obtainable by reaching level 120 in any skill. The achievement was first released on 12 April 2010 with the Dungeoneering skill and later expanded when master capes were released for other skills on 28 April 2014.

104,273,167 experience is required to reach level 120. This is about eight times the experience needed to reach level 99. The capes can be bought from the existing skill cape sellers for.

When a player reaches level 99 in Dungeoneering, they may continue to proceed to level 120 and receive a Dungeoneering master cape. Dungeoneering is the only skill that has levels above 99 - master capes for other skills are achieved when the experience required for level 120 is reached.

Master capes look different from the ordinary level 99 skill cape: the skill symbol is lower than on an ordinary skill cape, with particle smoke emitting from the bottom of the cape. The Dungeoneering master cape also has a unique emote while other master capes share their emote with their skill cape counterpart.

Reaching the requirement gives the message:

History
Jagex polled players about plans to add Master capes to all skills. The poll won with 63% of the votes. On 28 April 2014 the Master cape of Accomplishment was released. These capes are awarded for reaching the experience needed for level 120, which is 104,273,167. Skill levels are not increased accordingly, and the Master capes do not have their own emotes.

Trivia

 * There was once a glitch which, upon reaching level 115 Dungeoneering, would inform the player that they were level 120 on the hiscores.
 * Only one true mastery, provided with the Dungeoneering master cape, has an emote due to Dungeoneering continuing up to level 120. The other skills have a virtual level.
 * With the release of virtual levelling, players now have the ability to display all of their skills up to the maximum of 120. This offers no in-game benefits.