Mastery Tokens
From Melvor Idle
Mastery tokens can be claimed in the bank to earn a random mastery level for their corresponding skill. Mastery Tokens are earned randomly while skilling in a non-combat skill. When used, a mastery token will randomly apply a mastery level on an 'item' in that skill, including 99'd items. Different skills have different chances of receiving a mastery token please see the below table.