How do I upgrade skills?
Ceres M Guide
If you wish to upgrade the skills of your character in order for it to be stronger, you'll have to open up your hero detail of the character of your choice. From there, check the buttons on the right hand side and scroll down until you see the "Upgrade Skill" button.
Once you press that button, you'll see an interface that lists down your leader skill, as well as usable skills. The price for upgrading is displayed on the lower right side of the screen, then the amount of skill stones are listed beside the skill names. You must have enough skill stones and gold in order to upgrade a skill.
Skill stones vary per element so you need to check how much you have for your characters. Here are some ways in order for you to get them:
Rotational Events such as the Dice Game
Package section from the Shop