Broken VNM Yilbegan

Platform: Windows
ISP: Time Warner
Type of Internet Connection: CATV
Internet Connection Speed: 20Mbit/s
Date & Time: 12:24 AM EST 2/19/2013
Frequency: Sometimes (About 1/10 Yilbegan pops)
Character Name: Indigla
Race: Hume F
World: Bismarck
Main Job: RDM 99
Support Job: WHM
Area and Coordinates: Beaucedine Glacier H-7, area just east of the bottom of the ramp
Party or Solo: Party, 4 members
NPC Name: None
Monster Name: Yilbegan
Steps:

1. Traveled to Beaucedine Glacier from Xarcabard with a Black Abyssite in possession, no other VNM abyssites were in possession that would affect that zone.
2. Walked into the zone a bit and /heal-ed to search for Yilbegan and found a "strongly" reading just down the ramp from the Xarcabard zone.
3. Party buffed and I went to pop the NM.
4. NM popped without shadow and constantly faces the person with the most enmity (not just turn to them to use a TP move) which is not typical behavior for this NM having now popped over 40 of them. Most will stay in one position and let you maneuver around them to fight from different positions relative to the NM.
5. The NM then primarily uses Soul Douse which gives a 10 or 5 count Doom effect making this fight extremely difficult with the monster's high regain. It will still occasionally use Dark Star or Chaos Blast which can occur from any position relative to the monster.
6. Having popped so many of these this atypical behavior seems like a bug. It has happened to me twice in Beaucedine Glacier, once in West Sarutabaruta [S], and once in East Ronfaure.
7. Our party wiped which would normally have no issue killing this NM at 99, due to dealing with constant Soul Douse and Meteor x3 causing the NM to depop.
8. One time in the past this occurred with a shadowed Yilbegan in Beacedine Glacier which was extremely aggrivating given how much effort it takes to create Black Abyssites and the very low shadow rate for this NM (around 1/25 to 1/50 it seems like).