It is a possible reward from masterTreasure Trails and cannot be made through any skills. Despite being listed on the Grand Exchange for the maximum amount of coins, it is typically traded amongst players for tremendously more than that.
This item can be stored in the treasure chest of a costume room, provided that the master clue interface is opened before attempting to store the item. This requires a Mahogany treasure chest. Alternatively, the item can be used on the opened treasure chest to insert it without viewing the interface.
A player performs the Dragon pickaxe's special attack, Rock Knocker.
The 3rd age pickaxe's special attack, Rock Knocker, temporarily boosts the player's Mining level by 3 (players will need to have 65 Attack to utilise this special). This consumes 100% of the player's special attack energy. The boost degrades every 60 seconds, with your Mining level returning to normal after 3 minutes.
This effect is useful to increase the chance of successful rolls or to meet a Mining level requirement above the player's base level. When used alongside the Lightbearer ring, special attack energy regenerates twice as fast, making it viable to consistently mine rocks 1-2 levels higher than base.
Note that any levels boosted above 99 with the special attack will be treated as 99. Therefore, you will start to receive diminishing returns with the special attack at level 97 and 98, with there being no value in using the special at level 99.[1]