Sanguine Mist

You create a cloud of bloodsucking fog that drains the life from the living. Each living creature in the area when you Cast the Spell, aside from you, takes 6d6 void damage with a basic Fortitude save. Creatures in the area are Concealed, and all creatures outside the cloud become concealed to creatures within it.

The first time each round you Sustain this spell on subsequent turns, living creatures in the area take an additional (rank − 2)d6 void damage with another basic Fortitude save. You also gain temporary Hit Points equal to half the damage a single creature took when you Sustained the spell this turn; calculate these temporary Hit Points using the creature that took the most damage. These temporary Hit Points last for 1 minute.