I've tried all 3 levels of the enchantment, it doesn't add or multiply xp from killing mobs, still only get 3 or 7 exp per kill no matter what mob is killed using the enchantment.

@Metalteuffel You're either using an outdated version of the mod or something is wrong on your end. Please fill out the issue report properly, with the appropriate information as found here. Otherwise we cannot help you.

As the issue report was filled out incorrectly and lacks the necessary information to pursue a solution, it shall be closed.