I am lvl 15, and have some really powerful weapons (ayleid meteoric shock damage, elven two-handed sword, blade of the haunted etc.), but it takes forever to get one of these ancient gargoyles down, even when i have three summons hacking at them alongside me. I encountered two yesterday at haynote cave winding sump, and it was just miserable. Nothing else has given me so much trouble yet (I have yet to open the Oblivion gates, so I guess Balrogs might be worse).
Isn't there an elemental weakness for these creatures, like other creatures in OOO have? They also cannot be "creature commanded" by my spells either!
They are weak to Frost. They're from MMM/FCOM BTW.
Oscuro's Umbra is level 50. She also comes with Fortify Health Abilities (four of them), Fortify Acrobatics, Fortify Fatigue, Restore Fatigue, Restore Health, Resist Fire, Resist Frost, Resist Magic, Resist Normal Weapons, Resist Paralysis, Resist Poisons, Resist Shock and Spell Absorption.
Wow! Just wow...So how does anyone manage to best her?
Depends on chars as always. Basically, to best her (and other OOO bosses) in melee it's good to have as high AR as possible, e.g. to aim for 85. Also, high Agility. If you have access to AR 85 and high defense against magic (via Resist Magic, Spell Absorption, Reflect Spell) you can http://www.gamesas.com/index.php?/topic/1078987-oscuros-oblivion-overhaul-spoilers-thread-27/page__view__findpost__p__16325219.