So I'll simply explain the power levels in my fic. Let's start with the mobs at the bottom. Only use this for reference. Like a certain someone quoted 'Power levels are bullshit' and that quote really shines in DxD where one can get power through emotions and determination.
Low-Class – They are basically the fodders that can be found anywhere in Supernatural World. Still, they are more than enough to destroy a few buildings on their own.
P.S - Don't underestimate a mob xD
—Low Class Devils/ Reincarnated Devils
—2 Winged Angel/Fallen Angel
—Humans with normal sacred gears
Example - The Shit exorcist Freed Sellzen
Middle-Class – They are more powerful than Low-Class, enough to level a small town at their full power. In Underworld, they can gain the title of Baronet or Knight through merit.
—Middle Class Devils
—4 Winged Angel/Fallen Angel
—Low-Class Grim Reapers
Example - Xenovia equipped with Durandal in her debut.
High-Class – Powerful enough to destroy a town or two. Those at the top of this class can do so effortlessly. In Underworld, their ranks vary from Baron, Viscount, Count, Margrave, Marquis.
—High Class Devils
—6 Winged Angel/Fallen Angel
—Mid-Class Grim Reapers
—Sacred Gear Balance Breaker form
P.S- I'll not put every High-Class Devil who has yet to master their power in this Class. Having Demonic power equal to a High Class and not being able to fully control it puts them at Middle Class at worst or High Class at best.
Ultimate-Class – In Underworld, these are the big bois of their territory. They can destroy a city block if they feel like it. The power level varies a lot in this class. For example, we have Kuroka(The anime one) who excels in poison and magic while we have Sairaog who could literally bitch slap anyone in Ultimate Class despite being one himself.
Their ranks vary from Prince, Duke, Archduke, King, Great King and Satan.
—Ultimate Class Devils
—8 to 10 Winged Angel/Fallen Angel
—High-Class Grim Reapers
—Base Dragon King
—Longinus Balance Breaker form
Example - Yasaka *wipes the drool*, Kokabiel...
Satan-Class – The big bois of every faction. They can destroy a country like Japan with ease *points at a certain sis-con devil*
They are the top command of their own faction.
—The four original Satans
—12 Winged Angel/Fallen Angel
—Ultimate-Class Grim Reapers
Example - Azazel, Michael, Tiamat, Grayfia and Gabriel etc.
Low-Tier God – They are the beings who can equally fight with non-battle Gods such as Gods of Agriculture, Music etc.
—Every Low-Level God
Example - Serafall Leviathan, Falbium Asmodeus etc.
Mid-Tier Gods – This is the level for normal battle Gods. The power level varies a lot in this class from guys like Loki to Artemis. Yet they are more than enough to destroy several countries.
High-Tier God – This is the level for Chief Gods or everyone equal to them.
Example - Odin, Zeus, Thor, Vidar (Full powered with his Mystical boots)
Heavenly Dragon Class – This is the level for Heavenly Dragons or who won't get insta-killed by Heavenly Dragons.
Example - Fenrir at his prime, Crom Cruach (Evil Dragon), Ddraig, Albion etc.
Ultimate-Tier God – This is the level for the beings above Heavenly Dragon Class and Light Novel showed plenty of them. They can easily cause the world's destruction if they wants.
Example - Indra (God of Hindu Mythology), Sirzechs and Ajuka (Yes, these two really can really destroy world on their own), God of Bible (He was OP alright. He sealed the Trihexa on his own. That's the only reason he perished in Three-way war.)
Super-Tier God – The beings stronger than everyone except Ophis, Great Red and Trihexa. They can also destroy world but with ease.
Example - Shiva etc.
Dragon God/True Dragon/Apocalypse Beast – The only three beings in dxdverse qualifies for this Class and they are all OP as fuck. They can wipe out the whole universe.
?? – What? You thought this was best? Naw, there are beings far stronger than Great Red in great multiverse and they are end game boss who pops up in DLC content.