Rings of Shared Suffering

From Wayfinder's Guide to Eberron, page 117.

Description
Ring, uncommon (requires attunement).

These rings come in linked pairs. If you possess the Mark of Sentinel, you can use a bonus action to form a link to the creature attuned to the other ring; from then on, whenever that creature suffers damage, they only suffer half of that damage and you take the rest. This effect continues until you end it as a bonus action or until you or the other creature removes their ring. This effect isn't limited by range. A creature cannot be attuned to more than one ring of shared suffering.