Hard time tanking stronger monsters

[BruXsa]

Yep. I can tank Ice Fiends, but not Vamp Guards or Kvasir. I'm Brigid.

I had 89 AC when I tried, 97 with HP. Still couldn't tank Guards, let alone Kvasir.
My resists:

physical +99
magic -18
fire +5
electricity +0
cold +0
confusion +0
acid +0
drain +100
weapon magic +0
ghost hit +0
poison +0
slow +0
paralyze +0
turn undead +0
fear -25
cancellation +0
deplete +100
death +100
chaos +0
counterspell +0
god power +0
holy word +0
blind +20
life stealing +0

Last night, Jeff tanked Vamps and Kvasir with 87 AC. He's Ogma.

Alisa can tank Guards & Kvasir with 87 AC and she's Diancecht. Not sure what Alan's AC is, but he can also tank, and he's Govannon. Conq and Dripz can also tank, they're both Ogma and both have under 90 AC I believe.

Luke can also tank. He has 90 AC but I've seen him do it with 89. As of last night, he still has resists and granted spells from Brigid even though he's now Ogma.