As two actions, a tendril of inky darkness reaches out from you. When you cast the spell—and once on on each of your turns thereafter as an action—the tendril can touch a creature that you can touch or see within 10 meters to drain life from it. The creature must make a Reflex saving throw. If the creature is a construct or an undead, the spell has no effect on it.
On a failure, it takes 2d10 necrotic damage.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
You regain health equal to half the amount of necrotic damage dealt.
You can increase the damage by 1d10 for each additional mana expended.