Phlogiston is a fifth element beyond the four elements of Ancient Greece. According to Phlogiston theory, it's supposedly contained within all combustible bodies. It has no colour, odour, taste, or mass. Burning things releases it. Or would, if it existed, which it doesn't. But that should never get in the way of good gaming.
For more information, see Phlogiston Theory.
Game and Story Use
- Phlogiston may make a good phlebotinum, provided you can figure out a way to harvest it that doesn't consume it.
- It may have properties of fire, air, and plasma (physics).
- It may be magical or energetic.
- It may have anti-gravity properties. (Just extrapolating from that hole "heat rises" thing.)
- As a relative of the classic elements, it may form the body of an elemental creature.