Tether of Pain

You focus your own pain and anger to bind two creatures, within range, to each other. Creating a tether between the targets that is visible only to you and the targets of the spell. The tether appears as a swirling, black and purple string of arcane energy. If the spell takes, the targets are aware of the spell and it's effect.

Two targets of your choice, within range of the spell, must make a intelligence saving throw. On a success by any of the targets the spell does not have any effect. On a fail by both targets the damage dealt to one of the targets is also taken by the other. Any resistance or immunity still applies to the targets. The targets needs to stay within 300 ft. of each other for the spell to have any effect.

Both targets can repeat the saving throw at the end of their turn, ending the effect only after both targets succeed their saving throws consecutively.

Save DC = 8 + your intelligence modifier + proficiency bonus.

At higher levels. (17th level) You can target one additional creature.