Meditation is a skill which Luka learns indirectly from Alice. It costs 3 SP to use, and recovers half of Luka’s current health.
This skill is one of Luka’s most useful skills (if not the most useful), allowing Luka to take care of monsters which would normally be impossible. In drawn out battles, it is often advisible to use this skill combined with regular attacks and spirit defenses as opposed to powerful skills.
Alice originally mentioned meditation as a joke, only for Luka to try it and successfully heal himself, much to Alice's surprise and bemusement.