Lich's coffin

A "lich's coffin" was a term given to a special box designed to imprison an undying lich.

Known Lich's Coffins
In the Year of the Laughing Dead, 1056 DR, the lich Anthilar was severely incapacitated after a spell-battle in the streets of Tashluta in the Tashalar. Unconscious, he was trapped inside a lich's coffin and shipped north out of the city. His phylactery was not located. The intended destination was the Skullspire, a temple to Myrkul, the god of the dead, in Tulmon near the Lake of Steam, where the senior priests of the Conclave of Doom desired to study the lich. It never got there, and the lich's coffin changed ownership many times until at last it became part of the hoard of the mercury dragon Tostyn Alaerthmaugh in the Evermoors. It lay there, still unopened by 1374 DR.

Description
Anthilar's lich's coffin was fashioned from metal and described as massively armored. It levitated and stood upright. Tostyn was unable to open it by 1374 DR.