Basic Information
Ectoplasm1 is, essentially, a form of transient matter created by spiritual entities - or otherwise magically generated - to effect some kind of physical action. Thus a spirit might manifest a body for itself out of ectoplasm so that it can interact with solid objects2 or a wizard might conjure up a sword out of thin air by manifesting ectoplasm into a steel-like sword shaped object. Ectoplasm can also supply the necessary additional mass for shape-changing into a larger form3 and to make mask-like disguises.
The problem, of course, being that bit about "transient matter" - ectoplasm generation isn't a perfect mass-energy conversion; it takes ongoing magical exertion to keep it in existence, let alone shape and if the will or the power behind it is removed (say, because the wizard who manifested it is exhausted or distracted), it will tend towards a pale, slimy, sometimes faintly luminous substance which quickly "evaporates", leaving little or no trace4. This can be very embarrassing for the nervous, neophyte wizard whilst a true adept can usually train themselves to maintain a manifestation subconsciously. Supernatural entities tend not to have this problem - although few can manage this sort of performance, for those that can, doing so is as natural as breathing is to material beings5.
Naturally, for those who know what they are looking at, ectoplasm (usually of the slimy, residual variety), might as well be a neon sign advertising a supernatural component to whatever just happened … for those who don't, it's a material to give forensics personnel fits. Most of the time it vanishes before you can get it to the lab … and when it doesn't, it has no physical or chemical structure that you can analyse … as far as your instruments are concerned, there's nothing there. Even the light microscope doesn't show you any structure… Plus, ectoplasm also makes for weapons - and even perpetrators - that almost literally vanish into thin air, often having appeared out of nowhere in the first place.
Depending on who you ask, ectoplasm may or may not have a problem with sunlight.
Besides direct conjuration, some sources suggest that anything from "the otherworld" that is brought into physical reality may transform into ectoplasm unless consciously maintained. This may include air, water and similar things, possibly meaning that travellers emerge from a gateway covered in transient slime.
As previously noted, ectoplasm remains spiritual matter - and thus a physical body formed from it is still subject to warding as though it were a spirit - there may be some compromise in this, and it may be possible for a manifest entity to force its way past a ward, but this will usually come at the cost of significant damage. Ectoplasm may also be dispelled or banished by appropriate magics.
See Also
Sources
Game and Story Use
- Great stuff to turn up in the wainscot busting start of a campaign - or equally, as a flag that the monster of the month is a manifesting spirit type.
- Important to remember that anything made out of ectoplasm is not what it appears to be - iron made from ectoplasm is not iron and will not have the same bane effects on the fae, ectoplasmic copper might well not conduct worth a damn, ectoplasmic food will not support life…
- likewise, these materials probably cannot be worked or shaped in any form once conjured and attempts to do so will likely disrupt them (a sword made from ectoplasm, for example, probably won't bend, chip or break its tip off - it will either stay as it was first conjured or turn to slime and vanish). Physical properties generally will be prone to depend on the competence of the creator and actual functions will be magical simulations of what they appear to be (if I conjure a radio from ectoplasm, I get either a model of a radio or a prop to which I need to tie a communication spell).
- Interestingly a weapon made from ectoplasm might well be more effective in striking incorporeal opponents such as apparent spirits and other things that take limited notice of mundane weapons.
- Wounds inflicted on a body enhanced with (as opposed to formed from) ectoplasm may be tricky to adjudicate…