Passive abilities are  automatically triggered when you fulfill the trigger condition 

Active abilities are classified into Combat active and Field active.

- Combat active skills can be used when you find the enemy first. Skill button is located beside Attack/Escape.

 (Hart' Dissonance, Leon's Human Torpedo)

- Field active skill button is located beside Move,Rest, Stance button.

 (Zahir's Eye of Azrael, Isol's Recollection)