Promethians are a notable species in that they are always in a constant state of partial phase – unlike most characters in contemporary literature with the ability to phase – which serves to greatly reduce any damage dealt to them. Furthermore, by using the natural phase powers innate to their species, they can at times opt to completely phase themselves, eliminating any threat to their person by phasing out of sync with the dimension that they're in. This allows them to choose whether to walk through solid matter or to render themselves completely invisible and undetectable by all means, including magic.
The Promethians exist in two forms: namely, first- and second-stage Promethians. First-stage Promethians are 7 feet (2.1 m) to 10 feet (3.0 m) tall, are entirely "human" in the range of possible outlooks and alignments, and the natural phase abilities of their bodies renders any force or energies directed against them to cause no more than a point-for-point conversion to "Standard Damage Capacity" (termed S.D.C. in the Palladium game setting), no matter how powerful the originating force.
Those Promethians that manage to survive and pass the Test of Maturity are transformed into larger, more durable versions of their old selves that range from 15 feet (4.6 m) to 30 feet (9.1 m) in height. These creatures are immune to S.D.C. weapons; they each gain up to 2,400 points of what is termed "Mega Damage Capacity" (M.D.C.), and all attacks directed at them inflict only one-quarter damage, no matter how powerful the originating force. Second-stage Promethians make up the majority of the Promethians on the planet outside Center (actually, second-stage Promethians are found nowhere else in the Megaverse except on Phase World), and it is they who are the ones tasked with the universal mission of identifying and countering the greatest threats to the Megaverse. Second-stagers are also the ones who are possessed of "an alien way of thinking"[1] and do not live by morals as most other sentient beings understand them; they are prepared to do whatever it takes to safeguard the Megaverse, even if their actions appear "evil" to outside observers.