Some enemies at Night Mirror level dungeons and events have special passive abilities.
Anti-magic[]
Anti-ranged[]
Berserker[]
Chosen[]
This enemy has all his stats increased by 70% except Defense (increased by 170%) and Dodge (not modified at all).
Reflect[]
Regenerator[]
Enemy cast to itself +500 shield every turn after it received damage till max. hp. Same way work Unicorn skill of Unicorn Paladin and Stalwart skill of Dragoon or Platinum Dragoon.