It is also reminiscent of what we developed for the vampire moss...
Life Drain (Ex): As a swift action, a vampire moss can use negative energy to cause a persistent energy loss in a creature to which it has established a vampiric link. Such a creature loses 1 hit point each round. This continuing hit point loss cannot be stopped by a Heal check, cure spell, or heal spell, though these methods can restore drained hit points. The vampire moss gains temporary hit points equal to the number of hit points drained. If the vampiric link is severed, the hit point loss ceases immediately.
If the hit point loss continues for a full minute, the victim must succeed on a DC 13 Fortitude save or fall unconscious for 1 minute. For every round the link remains after that, a conscious victim must succeed on another Fortitude save with a cumulative +2 on the DC per round after the first, or fall unconscious for 1 minute. The save DC is Charisma-based.
After a vampire moss has drained a number of hit points equal to 4 times its own maximum hit point total (16 points for a typical vampire moss), it reaches satiation and severs the vampiric link.
Vampiric Link (Su): A vampire moss can drain the life from any living creature within 30 feet. To do so, it must be aware of the creature and take a standard action to attempt to establish a link. A vampire moss does not need to touch a creature to establish a link.
The target creature will feel a prickling sensation at the back of the neck, and must succeed on a DC 13 Fortitude save. On a successful save, the link fails to establish, though the vampire moss may attempt again on its next turn. A failed save indicates that the vampire moss has latched on and formed a supernatural link with the target.
The victim will not be automatically aware of the link, but must succeed on a DC 13 Will save to notice the attack. Each round the link remains entitles the creature to another Will save to sense the link, with a cumulative +2 bonus on the check per round after the first. Awareness of this link does not automatically confer the location or identity of the moss to the victim.
A single vampire moss cannot link to more than one creature at a time. If its victim dies before the moss's appetite has been sated, the moss seeks a new target to finish its feeding. If the victim moves more than 30 feet away from the feeding moss, or if the feeding moss is slain, the link is severed. A vampire moss can sever the link at any time as a free action. The save DCs are Charisma-based.