As far as i remember, we have x1 y1 x2 and y2 and therefore the precise width and height of a dungeon map as well as playerpositions, which would allow us to measure 5 yards range between people, guess thats what dbm will do again this time.
So where is your difficulty exactly?
Ultraxion:
"Defeat Ultraxion in Dragon Soul on Normal or Heroic Difficulty without any raid member being hit by Hour of Twilight more than once.
I havent done the fight myself or seen logs of it, but id say it should become visible in the combatlog as aura_applied or some sort of spelldmg taken on live realms