Vulnerability Hex

You mark a target creature in range with a hex to increase the damage of the next attack against it. The target creature muse make a Wisdom saving throw or it gains vulnerability to the damage from the next attack or spell that deals damage to it. 

If the creature has resistance or immunity to that damage type, ignore that instance of damage resistance and the creature takes normal damage.

Inspired by combat skills from Darkest Dungeon, a dungeon crawl rpg by Red Hook Studios.