Mace of Retribution

This mace was found with the remains of a cleric of Pelor, during a dungeon exploration.  It was gripped in the skeletal remains' left hand, and a holy symbol extended in the right.  Although the design of the mace appears dated by roughly a half century, it appears otherwise unremarkable.

Property: The mace glows a faint, shimmering, silver whenever undead are within 50 feet, regardless of walls or other obstacles.

Property: When wielded with undead within 50 feet, the mace wants to be used against them.  You gain +1d4 damage against undead each round, cumulative.  For example, on the third round of combat that includes undead, the mace would do +3d4 damage against them.  This bonus resets to 1d4 if you kill an undead with the mace.

Property: At the end of each round, if the mace has not killed an undead target, but undead are present, there is a chance that the built up power will be shunted to you.  You can avoid this fate by dropping the mace.  This negates the mace's magical properties until the next morning.  If you do not drop the mace, roll the d4s that correspond to the bonus damage of the mace for that round.  If any of the dice come up a 1, you take radiant damage equal to the total of the roll, and the mace resets to 1d4 bonus damage on the next round.