Ectoplasm

Ectoplasm was an insubstantial substance that resulted from the use of psionics  and some magic spells. It also formed the bodies of ghostly undead. Ectoplasm originated from the Astral Plane.

Description
Ectoplasm took various forms, depending on how it was manifested. In its original form, it could appear smoky, diaphanous, or as finely spun strands. Things made of this form of ectoplasm were visible only as wispy outlines, appearing ghost-like. Alternatively, in liquid form, it could be a goo or slime that was translucent and ephemeral. There were also semi-solid and solidified forms that were partially translucent and rippling. Ectoplasmic armor had mottled patterns that shifted with a wearer's mood. A crystalline form was also possible.

It was often grayish or silvery in hue, but other colors were possible depending on how it was shaped. It sometimes shimmered if it carried or resulted from a psionic effect and could appear pearlescent.

Properties
Ectoplasm was completely inert. It had no inherent special powers or properties of its own, only those imparted by the psionic powers that used it. For example, using wall of ectoplasm created solid ectoplasm that could not be bypassed by ethereal or incorporeal creatures. The spells ectoplasmic armor and ectoplasmic feedback also used ectoplasm to protect against incorporeal attacks. However, using certain psionic powers, unstable ectoplasm could be created that dissipated explosively, initially producing "hellish" flames and later different kinds of energy: fire, cold, electricity, or sonic. It was composed of particles but could be drawn into writhing strands.

Creation
Ectoplasm existed naturally on the Astral Plane, and could be part of the fundamental matter that went into the creation of demiplanes via the genesis power or spell. It was even part of the astral ecosystem: the spiders of an ectoplasmic swarm, which were native to the Astral Plane, produced raw ectoplasm as their waste and used raw ectoplasm to spin their webs.

The souls of those who'd died but not moved on to the Outer Planes could, over the course of days or months, gather incorporeal ectoplasm around them to give themselves form. In this way, they became undead, such as incorporeal ghosts or allips or corporeal bodaks, and other undead like the incorporeal quells and ghost brutes. The latter's ectoplasmic drool existed in both ethereal and corporeal forms, and dissipated on contact with non-living matter.

When a part of the astral medium was drawn into the Material Plane, it became raw ectoplasm. The manifestation of many psionic powers could, if not suppressed, produce a material display of ectoplasm as a seepage from the Astral Plane. The target or area became slicked or sheened with shimmering ectoplasmic goo, which evaporated after several seconds. A shimmering ectoplasmic film was also the effect of a dimensional anchor power.

Powers of the metacreativity discipline pulled raw ectoplasm and other matter from the Astral Plane for a psionics-user such as a shaper to fashion into objects and even pseudo-living constructs of their choosing. Such things were solid or semi-solid and as durable as normal matter, being held together by psionic energy for their duration. When ended or dispelled, they disappeared, leaving a few drops of liquid ectoplasm or a thin film of glistening ectoplasm that swiftly evaporated.

The ectoplasmic form power turned a being and what they wore or carried into ectoplasm. Originally, they could pass through solid matter like it wasn't there. Later, they became almost insubstantial and couldn't manipulate the world around them. They could only pass obstacles if there were small gaps, and couldn't pass through water.

The dismiss ectoplasm power caused all affected ectoplasmic objects and creatures that could not resist to dissipate to their constituent ectoplasm and subsequently evaporate in several seconds. A being in ectoplasmic form had a 50% chance of being obliterated or transported to a random spot in the Astral Plane.

Scholarship
"Sophisticated" psions understood that the sheen left by a material display of psionic manifestation was ectoplasm from the Astral Plane.

In the Gith language, "rzydu'un" meant "ectoplasmic blast".

Background
Ectoplasm is a substance claimed to be created by mediums, psychics, and spirits in spiritualism and paranormal studies, though most often hoaxed with normal materials. It was made famous as a slime left by ghosts in the Ghostbusters movies. In science, ectoplasm is the outer layer of a cell. Obviously, the first version is the inspiration for its link with psionics and ghosts in D&D.

The word "ectoplasm" is from the Greek words "ektos", meaning "outside", and "plasma", meaning ""something formed or molded". This incidentally suits its link with the Astral Plane, which lies outside most cosmologies, and its ability to be shaped in psionics.

Appearances

 * Novels:
 * House of Serpents
 * Venom's Taste
 * Viper's Kiss
 * Vanity's Brood