Any Planeswalker'll tell ya that the Planes are full of strange and wondrous creatures, and this is one of the strangest. The positive energy symbiote typically looks like a big blob of glowing energy, but you'll almost never see one looking like that. See, these things like to get inside a blood and set up kip. Once that happens there's no gettin' it out of it's new case, and most won't want it out. Why? Well, the symbiote works to keep its host alive, so it can benefit longer.

Combat: Symbiotes aren't all that much for fightin'. Most bloods will go their entire lives without ever seeing one or visiting its home Plane, and the symbiote would rather partner up with a body than kill it. That don't always happen, though. If pushed into a fight, the symbiote'll extrude a tentacle and start lashing out at what's threatening it. When it hits it infuses positive energy into its target. At first this can seem like a benefit, since it'll heal wounds and make a body feel better. A canny blood'll know better than to ignore this, though. It's positive energy and it can kill if you get too much [in game terms, once the target's hit points reach twice his maximum, he explodes--instant death, no save].

'Course, when a blood encounters one, he's likely to think he's under attack. The symbiote will choose a body at random (if there's more than one around at the time) and try to engulf him. The only way to avoid that is to dodge; armour won't help a bit against this [in game terms, only dexterity and magical armour class bonuses help]. Once it engulfs the terrified basher it'll seep into his body through his skin and disappear from sight. Once that happens, only the death of the host or high-powered spells will get the symbiote out.

Habitat/Society: Positive symbiotes have no society. They don't appear to interact with each other, or even acknowledge the existence of each other. They're content to "ooze" through their home plane. slowly searching for a body to enter.

Ecology: Y'can debate this one 'till forever comes. It's unknown what kind of ecology the positive energy plane has, but the symbiotes don't seem to interact much with whatever there is. In fact, some canny bloods don't even think they're really creatures. They think the symbiotes are a kind of elemental life, like regular elementals.

Positive symbiotes cannot live outside of their plane, unless they are within a host. If unprotected, the energy they are composed of slowly disperses into the environment and they die [in game terms, they lose 1 hit point per round until they are dead or have found a new host; living creatures nearby will become a little healthier, but not enough to be represented in game terms]. They appear to be able to reproduce only within a host, and that reproduction kills the poor sod when it happens (see "The Dark", below, for details).

The Dark: Positive energy symbiotes provide a few benefits to their host. First, the host is protected from the harmful effects of the positive energy plane. He can live there indefinitely, and will never explode. Second, the host doubles the hit points he receives back from any healing at all, whether natural or magical. Third, the host no longer needs to eat or drink to live (although eating and drinking are still required to heal naturally). Fourth, the host benefits from the magic resistance of the symbiote.

There are some drawbacks as well. When the heals, if the hit points recovered would take him above his normal maximum, they do. While this may seem like an advantage, it is not. Once this happens, a reproductive urge is triggered in the symbiote, which channels its energy directly into the host at the rate of one per round, until the host reaches twice his maximum. He then explodes, dying instantly, no saving throw. Afterwards, there are a number of new symbiotes scattered around equal to one-fourth the host's level, rounded up. The now-dead host cannot be restored to life with anything less than a wish spell. This fate may be evaded if the host suffers enough damage to bring him to his maximum hit points or lower, which stuns the symbiote and stops its reproductive drive. However, a save versus death magic (with Wisdom saving throw bonuses) is required to inflict damage upon one's own self.