Ambuscade Volume 2 - May 2017

I know that like no one does Vol 2 cuz efficiency blah blah but anyone know the gimmick to this guy? Keep seeing random high damage and have tried lots of things to force it but haven't been able to get anything consistent.

Haven't confirmed it personally, but from the 2ch.

Baleen Gurge - Takes extra physical damage
Angry Seas - Removes above damage bonus
Caudal Capacitor - Takes extra magic damage
Blowhole Blast - Removes above damage bonus

Might be easier to just do Vol 1 Easy solo but it depends on your job, hehe.