Transfiguration is a mod that allows you to possess a player, using a rare uncraftable item you can hit them with it, forcing them into spectator mode, and you to take their skin and name. (there are ways to reverse this)
SPOILERS:
Sanctium Frame Can be crafted by getting all 3 of the unique Sanctium Fragments located in the Holy Site structure.
Corrupted Sanctium Frame Can be created by holding a Sanctium Frame in your main hand, and a Sculk Catalyst in your offhand, right click and voilá Hitting a person with it destroys the artifact, and makes you possess their body
Talismen Bell The Talismen Bell can be found in the same structure as the Sanctium Fragments When right clicking anyone in a 20 block radius that is possessing someone will be dealt 5 Purification damage, upon a possessed person dying to Purification damage the original owner of the body will take control again. Every ring of the bell deals one damage to the item, and it has 100 health in total, you cannot repair it
