Displacer

 Touch a creature with the Replacer spell active on them. You must succeed a Charisma saving throw with the DC being the spell save DC of whoever cast Replacer. On failure, the spell completely fails. On success, you will reverse the effects of the spell, putting the foreign soul back in their body, which will appear in the closest open space that'll fit their body size.

If this is used more than once a long rest on the same target, even after a successful Charisma saving throw, the chance of it working is quartered which the DM must roll themselves.