Killed him with his own skull. Avenged Merioli. 

=====================================================================

You hold high the skull and a bolt of energy shoots out of it!
Your golden arrow hits Nithem the Lich.
You watch with self-pride as your golden arrow hits Nithem the Lich.
Nithem the Lich says 'I told you, you cannot defeat me.'
Nithem the Lich looks around in panic.
Nithem the Lich asks 'Hey, where is my phylactery?' 
Nithem the Lich says 'AAAARGHhhhhhhhhh'  
A blinding spark races along the stream of green light between you and Nithem
the Lich!
The skull draws some power from the kill.

Finally the Lich is DEAD, R.I.P.
Its skull falls onto the ground with a lifeless thud.

1085113: Nithem the Lich, skeletal figure in blood red robes 

You give a blindingly bright rift spark to Shaman.
Congratulations! You have just completed 'Armament longevity'
The energy drain on your entity weapons has decreased.