True skill mastery

True skill mastery is an achievement greater than skill mastery currently obtainable only by reaching level 120 in Dungeoneering. The achievement was released 12 April 2010 with the release of Dungeoneering. When a player reaches level 99 in Dungeoneering, they can continue to proceed to level 120 to receive a true skill cape. Currently, this is unique to Dungeoneering; thus it is not possible to (permanently) exceed level 99 in any other skill. The true mastery skill cape (according to the skill interface) does not look much different from the ordinary level 99 skill cape, and it is unknown if it will have a "true skill cape" emote, or any other additional bonuses.

104,273,166 experience is needed to reach level 120. This is about 8 times the experience as 'Skill Mastery'. No one has level 120 in Dungeoneering at this time and only 385 players (as of 16 July 2010) have reached level 99. It appears that Jagex currently has no plans to raise the level cap for any other skill .There are only floors up to level 69 (floor 35), so there are no special floors for true skill masters, although reaching level 120 does give a player the ability to bind up to four items. In the future, it is also very likely that it will give access to a very special area accessed by a Mysterious Entrance.

Trivia

 * It was thought that a glitch where most of the levels on the stats tab flash to level 120 for a quick second however many players now consider it to be an Easter egg by Jagex as the total level is 1337, meaning leet in leet speak.
 * If Daemonheim contained unique floors all the way up to True Skill Mastery, the highest floor would be floor 60, accessible at levels 119 and 120. True skill masters would not have their own floor. Except after the Dungeoneering update each floor environment has its own waiting room with a circle drawn in it (even the unreleased warped and chaotic). There is also a similar circle in the middle of the castle, which very likely has something to do with 120 Dungeoneering.
 * Judging by the in-game guide picture, the level 120 Dungeoneering cape has a gold trim.
 * On July 25, 2010, it appeared that one player had reached level 120 with only 63,785,841 experience (placing him in fact at level 115).
 * Jagex stated that True Skill Mastery of Dungeoneering will reveal more about the Strange Power event.