"This article is about a special category of damage increase effect in Dragon Nest: damage duplicator. The most prominent examples of this effect are the additional damage from Finishing Attack of gladiator and the Dark Elf Dance (Dance 2) of Dancer. The new assassin class introduces 2 new party buffs with dmg duplication effect as well." - Chaose5
Avery interesting read with useful information that I didn't know about.