The Pocketwatch of Eternity

PC version
The existence of The Pocketwatch of Eternity, is up for debate, legend says it was the final creation of Rundis.

This infamous pocketwatch, during its transformation from a storable timepiece to a magical artefact of forbidden arcane tradition drained 4 wizards, including Rundis, of not only all their spell slots but their very life essence; For Rundis had miscalculated the amount of energy needed to bind the spell into the item, it was the last miscalculation he had ever made.

It is very unlikely that the spell was successfully transferred into the item, but because of this level ten spells have been outlawed in the empire due to the danger to the casters and the surrounding area.

DM version
The spell did succeed, and it sucked the first part of Rundis is could into it, His body and personality, leaving behind his magical prowess, greed, and malice, and his sentience to the other items to split between themselves.

If somebody were to cast detect magic on it, the item gives off two auras, one of extremely powerful transmutation magic, the other of a trapped soul.

Rundis is trapped within his item suspended only semi-conscious but still himself. He experiences the outside world at one-quarter speed, and has only been stuck in this item, in his perspective, for 200 years. if one were to enter the item to talk to him, it would take him long to respond to anything, if one figures out how to communicate with him at all. He also is stuck in his own time loop, which he relives at 4 times the normal speed, he has relived his entire life many times as a bystander by now.