Ring of Herculean Might

The wearer of this ring is temporarily gifted with the strength of ten ordinary men. To activate its power, the ring must be placed on the hand and then held aloft for ten seconds. During that time, it is struck by multiple bolts of lightning that do no damage to the wearer, but will do standards Lightning damage (as per equivalent spell) to anyone unfortunate enough to be touching the wearer at the time.

That this exits, and that I do not own one, saddens me greatly. 

If the wearer takes any damage during the ten seconds that it takes the ring to activate, then the process fails and everyone except the wearer in a ten foot radius will take standard lightning damage. The ring cannot be used again for a twenty four hour period.  

Wearing the ring for more than a few minutes causes any user, regardless of race or class to first become short tempered, then ​progressively more angry until it builds into a berserker rage where they will murderously attack anyone in the vicinity, including loved ones.  The wearer is usually fine for about ten minutes, but for every ten minutes the ring is worn there is a ten percent chance (cumulative) of the wearer going berserk.

Once that happens, the character can only be stopped by death, unconsciousness or by the removal of the ring. They are immune to all spells of charm and sleep during this time.