Saddle of Shared Pain

Wondrous item, common (requires attunement by a ranger)

This sleek black saddle has tiny red veins that travel along its surface, pulsing whenever a creature wearing this saddle takes damage.

When you put this saddle on a beast and are at least within 10 feet of that beast, as a reaction whenever you would take damage, you can transfer to that beast an amount of damage equal to its Hit Dice.