Originally from Misfit Studio's "Metahuman Threat Levels" 3rd party rules, adapted for the Romverse.
The Paranormal Threat Scale
This scale, codified by a joint U.N. panel run by UNISON, is the officially recognized system of designating Superbeings and other Paranormal entities according to their power level, and the amount of force necessary to pacify them. It is currently in use by all major Government agencies dealing with Paranormal entities, such as UNISON, AEGIS and the Paranormal Regulation Agency, and most super-teams also use the ranking system.
In terms of growing threat:
Alpha - Minimal threat. Low-powered or modestly trained Paranormals. Can be handled by conventional law-enforcement.
Example: the average SHADOW trooper.
Beta - Beta-level Paranormals pose as much of a threat to typical law enforcement as an armed normal individual, and are at best to be handled by tactical response units, but can be held in normal detention facilities, provided caution is taken.
Example: your average Power-House Augmented thug, Fear-Master,
Gamma - This is the standard level at which point a Paranormal is recognized as a "Super", in regards to power level and destructive potential. These require special Anti-Super tactics units to deal with, and special containment procedures are necessary for long-term holding.
Example: the Average Supervillain.
Delta - Extremely powerful and dangerous Paranormals, these are capable of wide-scale devastation, and are a high-level threat to life and society. Full military responses are usually required, but Delta-level threats are best handled by other Paranormals or comparable beings or forces. Special Containment Procedures are always necessary for long-term holding.
Examples: MyuTwo, Gamma the Atom-Smasher, the Cosmic Mind
Epsilon - Also still classified as "Sovereign" class in some old filing systems, as Paranormals of this power level are legally considered sovereign nations by International law. Their residences are embassies, they're considered visiting heads of state, and their fights are wars. Their power level is such that entire nations, continents, or even worlds are considered at risk. Vast resources are expended just to anticipate and counter potential rampages. The forces of comparable Paranormals, or the concerted efforts of multiple Paranormals, are required to neutralize their threat, and unique containment procedures are required to attempt containment.
Examples: Doctor Destroyer, Malador the Mystic, Mechanon, Hades
Omega - Omega level beings are considered cosmic-level threats, either threatening entire intergalactic communities, or menacing the fabric of reality itself. These are often galactic conquerors, outer-dimensional menaces, or reality-warping cosmic entities. They can only be defeated by legendary amounts of resistance from lesser beings, the use of an Artifact of Cosmic Power, the intervention of an opposing Omega-level entity, or through trickery or diplomacy.
Examples: Lord Omega of the Terminus; Tyrannon the Conqueror; Empress Ist'vahna
On top of these, there are special notations:
"Arc” Notation: When added to a threat level, this notation indicates the threat is arcane/magical in nature.
"ET” Notation: When added to a threat level, this notation indicates the threat is extraterrestrial (alien) in nature.
“Dim” Notation: When added to a threat level, this notation indicates the threat is extradimensional (from another plane of existence) in nature.
“Psi” Notation: When added to a threat level, this notation indicates the threat is psychic in nature.
“Poke” Notation: When added to a threat level, this notation indicates the threat is Pokemorphic in nature.
"Mech" Notation: When added to a threat level, this notation indicates the threat is Mechanical in nature.
"Terra" Notation: When added to a threat level, this notation indicates the threat is of Terran nature, but not an Anthro.