We’re deploying a hotfix late tonight that will reduce the number of Lesser Charms of Good Fortune required to purchase 3 Mogu Runes of Fate from 90 down to 50. Meaning when you log in Wednesday and purchase your 3 Mogu Runes of Fate, which are used for 5.2 raid boss bonus rolls, it will only cost you 50 Lesser Charms.
We recommend waiting until after the scheduled Wednesday maintenance to ensure this change has gone through before purchasing your Runes.