The "best" solution to fix it is probably going to be dropping monster stats/drops onto the G_ monsters and hijacking a bunch of "real" monster IDs to use elsewhere. If you sat down and put the effort in and freed up a large enough number of monsters it's probably only something you'd have to do once.
Trip report:
Just went down there with Wizard/Priest and here's some highlights.
The MVP has real atk values, the Caster has average int (I'd recommend a little bit more), the Melee/Ranged both need actual atk values. Health values seem alright, they range from 300-500k and the MVP has 5mil (too much probably). None of them are boss flagged (including the MVP) so they all froze to the Wizard, but with their high health values they still took a while to die. You could probably clear through it alright with a geared Champ/Priest/Scholar.
Ranged - Doesnt really do anything, barely any skill use, the only thing I actually noticed was a double strafe. Damage was low due to low atk values.
Caster - Cool. Has a wide variety of abilities with some different elements, you can default Aqua and avoid most of the scary things. Damage is a little low probably.
Melee - Like the Ranged, didnt do a lot. We noticed it backslide once and I got fibered once. Damage was low due to atk values.
MVP - Tankable with Pneuma, not sure if this is intended. Hits reasonably hard ~1-1.5k per hit. Has a LOT of skills, they're not terribly scary though. It's hard to judge how hard it'd be without a mob, but I'd say it's definitely on the weak side right now.
I'm not sure how SinX/Sniper would do down there, it's a lot of health and they have a fairly wide array of defense/elements. But Champ/Wiz seem like strong potential killers for small groups of 3-4.
Damage was set to what we posted in the thread. I will look through the AI and see how we can improve them...