REC is a special type of points earned thru a variety of means and used to increase a character's knowhow.
The primary means of earning REC is thru defeating Bosses within 20 levels and Elite Monsters within 10 levels of a character. There are a few items that also provide REC. Extra REC is also earned thru performing Daily Activities and completing the Daily Guide.
A portion of a character's REC is lost whenever they die. The amount lost is reduced based on the VIP of a character.