Mod Moltare hinted that the function of the perk can be discovered by analysing timestamps and that the perk does not do anything that would make it useful to high-level players. After he left Jagex, he posted one more hint on Twitter  stating that the perk triggers under the same circumstances as other perks, and when it does, it rolls a number between 0 and 19, which is then compared to the perk's rank.
^Mod Moltare. Mysterious Perk: Tests Inconclusive. reddit.com. 12 April 2017. "Those testing it: you may find it helpful to keep some screenshots with timestamps, for later reference."*
^Mod Moltare. Do we know what Mysterious Perk does?. reddit.com. 16 September 2016. "Can confirm only that (a) it is not just an empty perk, and (b) it doesn't do anything that would lead top-end players to consider it mandatory for skilling, bossing or PvP."*