A high Dexterity(16+) with good armour and accessories should work try a potion of defense. Potion of defense can be bought from Sorcerous Sundries in East Balder's Gate. What I used in Black Pit again a Fighter with base DEX 18 (-4 AC).
NB. Use a Potion of Agility to gain a base Dex 18 if it is under 18, alternatively;
Take a potion Mind Focusing - DEX +3 (-1/-2 AC) You can drink multiple of these and it stacks up to DEX 25
Take a potion of Defense (Base AC 0)
The Dusty Rose Ioun Stone Helm (-1 AC)
Pellan's Shield +2 (-3 AC)
The Guards ring +2 (-2 AC) or Improved Cloak of Protection +2 (-2 AC)
Boots of Phasing (-2 AC)
Caste the level 4 Priest spell Defensive Harmony (-2 AC)