This glitch uses something posted on the forum a while ago and it is the infinite use of merge shop items to get free class boosts.
1) do one of joy's daily quests to get 3 realm gems
2) go to the merge shop and select the class boost
3) hold alt then click buy
4) quickly hit f4 to close your game
when you relog you will have the class boost and realm gems allowing you to repeat as many times as needed.
note: I don't take credit for this all credit goes to Gøld who posted about this glitch 3 weeks ago this is just the most practical use I have found.
Link to the thread that showed me the glitch will be in the comments hopefully