Astral Thorn Bind

A set spell that encircles the target in thorns. Although the skill on its own deals no damage, the thorns deal extra damage when the target is hit by an ally's physical attack, when the thorns are broken by an allies attack they are hit for 3d6 per thorn. Damage rises by 1d6 per thorn as level rises. The target is entangled with 3 thorns, and has to make a Wisdom saving throw to break free. 

When the thorns are broken by attackers, the attacks damage is added on to the thorns damage.