Toward the end of the fight my toon seemed to get punted to another room where a bunch of named Guards engaged me. Luckily my druid invulnerability proc went off. Meanwhile my merc continued the good fight on his own and even though he quickly got overwhelmed he must have been able to finish off the Arch Lich because I got credit for the kill.
I did use Paralytic Spray at one point to push back the skellie adds. I guess it's possible one of them got pushed into another room, perhaps even thru a wall. But there are no named Guards in the room where this Arch Lich spawns so this was either a bug or a real oddity.
Everquest: Surprises Around Every Corner!