True skill mastery is an achievement greater than skill mastery so far only obtainable by reaching level 120 Dungeoneering. The achievement was released 12 April 2010 with the Dungeoneering skill. When a player reaches level 99 in Dungeoneering, they may continue to proceed to level 120 and receive a Dungeoneering master cape. This is unique to Dungeoneering; thus it is impossible to exceed level 99 permanently in any other skill. The master cape looks different from the ordinary level 99 skill cape (it has the same shape as a Castle Wars cape, the Dungeoneering symbol is lower than on an ordinary skillcape, and black particle smoke emanates from the bottom of the cape.) and it has its own emote. The emote shows the player killing various Dungeoneering bosses, using all three sides of the combat triangle. 104,273,167 experience points are needed to reach level 120. This is about eight times the experience needed to reach level 99.Jagex has confirmed that at this time there are no current plans to increase other skills above level 99.
As of 21 May 2013, there are 7,785 players that have achieved level 120 in Dungeoneering.
- There was a glitch that when you reach level 115 Dungeoneering, it would say you are level 120 on high scores despite saying level 115 in your stats. Jagex eventually fixed them to reflect the proper levels.
- While the old combat system was in effect, if the level cap on all combat skills were raised to 120, the maximum combat level would still be 242. If the level cap on all skills were raised to 120, the maximum total level would be 3000 and the minimum overall experience required would be 2,606,829,175.
- When a player gets exact experience needed for 120 Dungeoneering (104,273,166), the player doesn't level up, but instead, the experience remainder shows zero. Getting 1 or more experience levels you up.
- It is possible to reach level 120 Dungeoneering when you reach 94,793,788 experience and spend all your tokens on experience, assuming that you haven't spent any tokens on rewards.