Demons and Devils are two different types of evils that can be summoned using Summon Demon/Devil and the Arcane Circle in Mind Weave. Here I attempt to outline how these creatures are related to the parts of the arcane circle and how they behave in the game.
Mind Weave Demons are destructive and chaotic. They are elemental in their powers and nature, associated with the six Elemental Spirits of the arcane circle: fire, wind, ice, water, earth, and lightning demons. Though they are entirely physical in form, their association with the Elemental Spirits means they are sometimes called Evil Spirits.
The six classes of demons each come in four different power tiers: lesser, common, greater, and epic. The lesser demons are mostly physical and animal-like in their abilities, attacking with claws; they have only defensive or mobilizing abilities associated with their elemental class. The common demons have better armor, health and stats, but also have a minor power associated with their elemental class, usually one usable in battle. The greater demons have a little more strength, but they have major powers useful for defense and attack associated with their elemental class. Finally, the epic demons are still stronger and have extreme powers that allow them to fight large groups and powerful enemies.
When a demon is summoned, it is more prone to accept tasks that have a clear end and freedom for them to execute the tasks in their own way. They prefer evil tasks to good tasks and neutral tasks. They consider the difficulty of the task only very little and are fairly likely to accept tasks that will almost certainly end in their death.
Mind Weave Devils are much more organized than the Demons, having a very strict social structure and political intrigues between their factions. They are associated with the six temperaments of the arcane circle: Ruling Devils or Nobles(Sar), Messenger Devils (Ros), Natural Devils or Shapeshifters (Neta), Occult Devils or Spell Weavers (Dain), Brute Devils (Ku), and Ambassadorial Devils or The Shamed Ones (Ra). Because of this association with the temperaments, they can be called Evil Temperaments or Temperamentals. The six factions have influence and power in devil society based on the radial distance of their temperament from the Sar (Evil) temperament. The Sar devils rule, the Ra devils are outcasts.
Devils in each temperamental faction are divided into 5 tiers as with demons: Arch Devils, Greater Devils, Misfit Devils, Lesser Devils, and Devilish Spawn (Imps). There are 11 types of devils in each faction (4 Arch, 2 Greater, 2 Misfits, 2 Lesser, and 1 Imp) for a total of 66 varieties of devil. These varieties are much more diverse than demons. Their stats more resemble those of humanoids than demons’ do and their power scales in a fashion like levels from Imp (Level 2), to Lesser (Level 4), to Misfit (Level 8), to Greater (Level 16), to Arch (Level 32). The four Arch Devils of each faction are unique and extremely powerful, but the other tiers have numerous members of each type.
Most Mind Weave devils have names that come from a variety of cultures, including Germanic, Celtic, Chinese, Hindi, Semitic, and Christian lore and demonology. The lore behind these names has been drawn upon to determine their powers and behavior.
At this time, I have yet to write up 25 of the devils (1 Ambassadorial Misfit and the 24 Arch Devils) but with a nearly 99% chance my players summon one I have made, so far I have had little motivation to make the rest. Maybe over the holidays I’ll write a few more.