[Taqwus]

Slap it with the Staff of Kurgi, or Magebane. Or shoot it with a Black Bow of Botulf. Or use Gate Cleavers and other fun toys combined with Curse. Or use physically strong units with Weapons of Sharpness. Or even a horde of Manikin might be able to kill it via armor-negating fatigue attacks. Or just preach it to death...