Level Up Reward Box Guide
From ggFTW Trickster Wiki
Periodically, when your character levels up (base, not TM) a message will tell you that you have received a gift from Megalo Company. You can access this gift from the MyShop window.
You can find an accurate list of level up rewards on the LifeTO website. Currently, the link is: https://lifeto.co/server-information/