Murphy's Hand is a Newbie-trap: Don't use it. Your Hero gains 1 point of corruption each turn in combat.
It's basicly a last resort item against very difficult bosses. But i can asure you that it's possible to beat all bosses in the game, even optional bosses, without Murphy's Hand. High Endurance [Opinion; 7-8 END for high-STR builds and 10 - 12 END for low-STR Builds] and resulting high Defense (20+) is the key to win even the toughest Boss battles.