Killed today. Took about two hours to spawn it, clearing out every one of the THF and BLM type tonberry in the area. (Imprecator and Pursuer maybe?)
Easy fight with 75thf/nin tanking, 75drg, 75whm, and 68 whm. He didn't use Throat Stab and used Grudge only once. We pulled it before it summoned a pet and he didn't summon during the fight. No instant summon + astral flow like a lot of SMN type NM's use.
Asklepios obtained, I believe it is a 100% drop.