Exhaustive Touch

Your hand glows with a pale green light, as you touch a creature, the energy saps away the spiritual force of the creature.  The creature must make a Constitution saving throw. On a failed save, the creature gains one level of exhaustion, levels of exhaustion stack. On a successful save or time runs out, the spell ends and any levels of exhaustion caused by this spell go away.  The creature may make a Constitution saving throw at the end of its turn to end the spell effects early.