Am I the only one who's had Zellaka at the end of K85 (group) be bugged lately? His running animations are not working, and he just blinks around the room, suddenly showing up right in front of whoever he's after. Seems I've only noticed this since this last maintenance.
As a fresh 85 it makes it hard to heal when he just pops up to you and one shots you.
Elemental resists in armor really helps. R-grade locations are mostly earth, fire and dark mobs so stick wind, water and holy stones to your armor. Also depending on your class use survival ("oh ****!") skills. He usually uses one hit and then moves to another target plus he uses unpleasant AOE. Read what skill he casts and step back from him, so if you survive one hit till healer gets you, tank grabs back aggro or Zellaka attacks somebody else you will be fine.