Low-class: These are the weakest beings in the High School DxD universe, typically possessing abilities that are only slightly above those of a normal human. Examples include enhanced strength, speed, and durability.
Mid-class: These beings are stronger than Low-class beings, but they are still not considered to be a major threat to the more powerful characters in the series. Examples include enhanced regeneration, limited flight, and the ability to manipulate small amounts of energy.
High-class: These beings are considered to be a significant threat to Low-class and Mid-class beings. They possess powerful abilities that can cause significant damage and destruction. Examples include advanced regeneration, the ability to manipulate elemental forces, and the ability to control other beings.
Ultimate-class: These beings are among the more powerful players in the High School DxD universe. They possess incredible powers that allow them to defeat High-class beings with relative ease.
Maou/Satan-class: These beings are the rulers of the Underworld and possess immense power that surpasses even that of Ultimate-class beings.
God-class: These beings are nearly the highest tier of power in the High School DxD universe. Examples Include Loki and Thor.
Transcendant/Primordial Class: This class of power is reserved for the original primordial which ranges from to Gaia to Tartarus.
Heveanly Dragon Class: This class has been reached by a few with those being Ddraig, Albion and Crom Crauch. At this level of power destroying the planet becomes easy and killing gods a pastime.
High God Class: This class is reserved to a level of power comparable to the strongest heads of various pantheons. Examples include the Biblical God Shiva and Indra.
Dragon God Class: This class is near unreachable by any but three that have existed since the beginning of the universe with those three being Great Red, Trihexa, and Ophis. These three are considered nearly omnipotent, as well as omniscient.
EXE Gods: Unknown (Pure Bullshit)