I saw 6 49+ PC's go after him. It looked like a well balanced group, but all the guards had really high MR, so if your going after him good luck. They all died fast because of the guard patrols
If i remember correctly, the king doesnt respond to hails.
The best bet would be to be invis, have a druid cast harmony on the king and pull the guards to zone, then everyone un-invis and attack while the guards are gone.
I've been wanting to kill this guy with some friends for a while.. also interested if anyone has killed him and his guards (surely someone has). Any information would be greatly appreciated.