jiè shī huán hún
lit. reincarnated in sb else's body (idiom); fig. a discarded or discredited idea returns in another guise
借
jiè
variant of 借[jie4]
尸
shī
(bound form) corpse
还
huán
to pay back
魂
hún
soul; spirit; immortal soul (that can be detached from the body)