I was fighting Kteng's wraith and it brandished a staff that caused another mob in the room to attack it. I entered a flee command, and the mud hanged.
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<628hp 264m 415mv 24900tnl (civilized - fighting - 7 AM)>
Kteng's wraith dodges your flaming bite.
You try to attack some empty air near Kteng's wraith.
Kteng's wraith parries your flaming bite.
An invisible servant tries to attack some empty air near Kteng's wraith.
You dodge Kteng's wraith's asphyxiation.
Kteng's wraith is covered with bleeding wounds.

<628hp 264m 415mv 24900tnl (civilized - fighting - 7 AM)> flee

I looked through the logs, and it actually looks like someone rebooted the server (not the mud itself, the entire server).