Life Tether

Choose a creature you can see within range. The target must make a Wisdom saving throw. On a failed save, a sickly green tether forms between you and your target. Whenever you take damage, the tethered target takes half as much damage (round down) as Necrotic damage. If the target drops to 0 Hit Points before this spell ends, you can take a Bonus Action to move the tether to a new creature you can see within range. The new target must succeed on a Wisdom saving throw or be tethered.

Using a Higher-Level Spell Slot. You can create additional tethers with a spell slot of level 4 (two tethers), 6 (three tethers), or 8 (four tethers).