How can I unlock new Abilities?
Each regiment has two Abilities, an active and a passive Ability.
To unlock the active ability for a regiment, they need to have achieved at least Star Level 1. A regiment's passive ability is unlocked upon reaching Star Level 2.
It is possible to use an active ability once per battle, while a passive ability will apply its effect during the entire time spent in battle, for as long as the regiment is not defeated.