I found out and am just throwing this out there.Probably known, but just trying to help.
When he casts "Unknown Condition" on you, it's actually a Retrograde, or a Subversion.Both same thing.Make him attack you when you have it on and you'll get higher hp.Just NEVER heal yourself or a teammate with it on you or them, as it will just bring them lower.
So good luck, if you can't hit too high, just do it slowly, he's not all that strong.
