Christine's Gem of Life Transference

It is said that there was an ancient ritual, time-consuming and difficult, that allowed a magic-user to transfer their life into an animal, and while their life was not in them, they could not be killed. The Empress Christine, impatient with the length and cost of the ritual, created this artifact to shorten the process.

This artifact is a small blue gem about the size of a plum. It allows the bearer to transfer their life to a vessel, either an animal or a specially made object. Inside, strange runes swirl around. When placed against the bearer's forehead, it takes one round to extract the life, after which there is a glowing ball in the middle of the gem, surrounded by the runes. If the owner then places the gem against the forehead of an animal or a specially made object, the runes form a tunnel, and the glowing ball appears to fall down the tunnel. The animal must be an ordinary animal and at least the size of a songbird.

If the bearer fails to transfer the life into a person or object within one minute, the glowing ball dissipates with no harm to the bearer. Once the life has been transferred, the bearer cannot be killed. Any attack which would reduce the bearer to zero hit points or less does zero damage, though other effects take place as if the bearer took damage, excepting any effect which would kill the bearer. If the vessel is killed, the life returns to the bearer, and the bearer may be killed normally.

It makes the bearer uncomfortable to be in the same room as the vessel, causing them to suffer disadvantage on all to hit rolls, skill checks, and saving throws.