I & II. Heals all of the damage from the most recent attack. Shares a cooldown with other Heal Wound spells. Heal Wound I has a cooldown of 3 rounds, while Heal Wound II has a cooldown of 2 rounds.
Due to the nature of healing in the game, it's best used after a big hit rather than a small one to maximize it's effectiveness. If double shot, burst fire, full auto are used against the PC it will only heal the damage from the last hit.