Vampiric Touch

The material below is Open Game Content from a 3PP Source

Vampiric touch
School necromancy; Level magus 3, sorcerer/wizard 3, witch 3
Casting Time 1 standard action
Components V, S
Range touch
Target living creature touched
Duration instantaneous/1 hour; see text
Saving Throw none; Spell Resistance yes

You must succeed on a melee touch attack. Your touch deals 1d6 points of damage per two caster levels (maximum 10d6). You gain temporary hit points equal to the damage you deal. You can’t gain more than the subject’s current hit points + the subject’s Constitution score (which is enough to kill the subject). The temporary hit points disappear 1 hour later.

SRD