Though demons come in many shapes and sizes, they can be sorted into tiers based on their abilities. The first tier contains demons of low consequence while the seventh tier is reserved for the seven archdemons, which could potentially destroy worlds if given the chance. Thankfully, most demons are bound to the Nether planes and cannot cross into the mortal realm without help.
First Tier
Simple demons, particularly ones like hellhounds. No shapeshifting abilities and lacking the ability to speak, cast magic or make deals.
Second Tier
Basic, low-intelligence elemental demons. Unable to cast magic or make deals, though they can control their specific element to some degree.
Third Tier
Low-level demons with the ability to make deals. They cannot take their own form in the mortal realms and must use a vessel, but they can cast many forms of magic to some degree.
Fourth Tier
Mid-level demons with the ability to make deals that cost mortals their souls. They can take a unique form in the mortal realm, but it requires sacrifices and rituals – additionally, their powers vary but cannot exceed the power of the souls used in the sacrificial summoning.
Fifth Tier
High-level demons that have the ability to enter the mortal realm in any form if given the opportunity. These demons have the ability to curse entire bloodlines, though their power can vary widely, and are able to cast powerful magic.
Sixth Tier
Major demons that can cause massive destruction if given the chance, and can even corrupt angelic being. Plague demons and Apocalyptic demons are the most common, though there are also extremely powerful elemental demons.
Seventh Tier
Archdemons – they cannot be killed and hold monumental power. Mammon, Asmodeus, Beelzebub, Belphegor, Paimon, Belial, and Amaymon.