Materia Keeper

HP MP EXP Gained AP Gained Gil Gained Steal Spoils Morph Location
8400 300 3000 200 2400 Jem Ring Mt. Nibel Reactor

Attacks

Big Horn
Hell Combo
Trine

Stratagy:

The Materia Keeper is a physical monster. A wise defense would put your characters in the back row. Use Long Range materia or characters with long range weapons to lessen physical damage. Casting the enemy skill Big Guard will put up barrier and further lessen the damage you recieve.
Materia Keeper absorbs fire damage, so don't use Fire or Ifrit. Use any other summons, magic, or attacks to destroy it.
When it attacks with Hell Combo, it hits one of your characters with each of its six legs for big damage. A Hi-Potion or Cure 2 wouldn't hurt after one of those.