Cauldron of Blood

You cause a chosen creature to bleed from its orifices as you draw out its life force and use it to heal or invigorate other creatures. The spell ends if the chosen creature is reduced to 0 hit points or it makes a successful Constitution saving throw at the beginning of its turn.

Until the spell ends, the chosen creature takes 1d8 necrotic damage on each of your turns while you or another creature you designate gains the same number of hit points. You, the chosen creature, and the recipient of its life force must all be within mutual spell range for this transfer to occur. If a creature is already at full hit points, they gain the victim's life force as temporary hit points instead.

This spell only affects living creatures and does not work on undead or constructs.