Bands of Shared Essence

This gold ring consists of two intertwined bands. They can be worn together, as a single ring, or separated and worn by two creatures. If the bands are separated, second, translucent band appears around each of them, as long as the wearers are attuned to the bands and on the same plane of existence.

If both bands are worn by the same creature, their hit points maximum increases by a number equal to their level. This increase lasts as long as the creature is attuned to the ring.

If each band is worn by a different creature, their life essence is combined and they share a pool of hit points equal to their combined hit points maximums. After attunement, the hit points are divided equally, but wearers can use an action at any point to transfer 3d8 hit points to the other wearer. The pool of hit points can be divided however the wearers wish and healing spells and damage work normally, but the sum of their hit points can never exceed their shared pool maximum. (example - before attunement wearers' HP maximums were 20 and 30. After attunement they transferred HP so that first wearer has 10 HP and the second wearer has 40 HP. Healing spells will not work on the first wearer until one or both of them take damage, bringing their combined HP below 50)

For these effects to work, both wearers must be willing, attuned to the ring and on the same plane of existence. They are always aware when the other wearer is injured. If at any point the wearers are on different planes of existence, the link is broken and the rings become inert, restoring each wearer's hit points maximum to its original value (their current hit points remain the same, unless they exceed their original hit point maximum, in which case the additional hit points are lost). To reactivate the link, the wearers must once again be on the same plane and must attune to the ring again.

If one of the wearers dies while attuned to the ring, the other wearer must make a DC 16 Wisdom saving throw, taking 3d8 psychic damage on a failed save and half as much on a success. The link then breaks, ring becomes inert and both wearers' hit point maximums return to their original value.