This is NOT an easy quest, the mobs for the final hail and kill are deep in Charassis, past many see invis mobs, you need to go south through the zone to get east, when you get to the room of the hail mob, it has 4 SI golems close to each other and a roamer to get past.
Highly suggest having a full group and killing your way through the zone, too many see invis to sneak through much, highly suggest having crowd control. The final mob kill is not difficult, trash mob difficulty, it's just getting to the mob that's hard.
If you can get a COTH across all or even part of the zone toward final hail mob, it sure helps.