First off it's for hord... umm Destruction only.
The exploit is in Dark Elf Ch7 PQ named The Griffon Gate.
Whenever the public quest changes from stage II to stage III, the old mobs run to despawn near the gate.
Another time when the exlpoit works is the time after PQ failure in stage III, when the new mobs run to their places from the gate.
Right there during the mobs running or when they have just spawned they can be one-hitted with like under 100 dmg.
You will get full exp from them (242xp as level 15) and 100 influence.
Sometimes the spawns will be pretty small but if ure alone and need inf and some xp you'll get pretty good pulls
+ this might be good chance to level low levels