Murphy's Ghost

This is a unique monster that can be found in the first maze level of Wizardry: Proving Grounds of the Mad Overlord. The ghost appear when the party searches the gem encrusted statue of a hooded man at 13E/5N. Unidentified, the monster appears as an "unseen entity". It doesn't do much damage, but is nonetheless relatively hard to kill for a party of rookies.

The point of this creature is to grind up your stats so that you can face the next floors below. The amount of experience he gives is much higher than any enemy you face in the early levels.

Tactics
Despite the low amount of damage, the high AC of the opponent makes it difficult to defeat. Despite being a ghost, it is not susceptible to dispelling. (Unless you're playing the SNES Japanese compilation, where you can dispell it.) The best tactic is to raise the party's AC by using Priest spells, while attacking with your melee characters; as well, use spells such as Katino to cause it to sleep, which allows your party to hit the monster much easily. While early spells such as Halito and Dilto won't be effective, later your party may be capable of using higher level spells to deal increased damage.

Trivia

 * According to the manual, two of the game's playtesters have the surname of Murphy: Helen Murphy and Paul Murphy.