Skill use mana and should be used as needed to quickly dispatch enemies. Use the mana potions dropped by enemies to regain it as needed.
Sliding
Slide to dodge out of danger quickly by swiping in a safe direction. Note: Because of its two second cooldown you will not be able to use it too quickly in succession.
Stars
Every level has three stars that can be earned. The first star is awarded by completing the level. The second and third stars have various objectives. Complete all three of them for the best rewards.
Upgrades
Equipment can be improved through a "star-up" process that requires materials and spending gold. Upgrade the equipment you like the best and want to keep relevant.