Life Tether Ankh

This pair of magical ankhs bind the lives of their
wearers. Any damage suffered by a creature
wearing one of the ankhs that would reduce them
below 1 hit point is instead suffered by the bearer
of the other, until both creatures are unconscious.
Each round a bearer transfers damage to their
ankh partner, they suffer a point of exhaustion.
If both ankh bearers are reduced to 0 hit points,
then the ankhs are destroyed.