Devils
Devils are fiends forced to share the plane of Hell with Demons. Devils themselves are always at conflict with Demons, and reside mostly in and near the fiery lakes of hell, whereas demons prefer the endless mountains of Hell.
Devils draw power from contracts, and all Devils can offer the service of themselves or their lesser as payment for contracts. They are also able to manifest magical weapons and other items seemingly from nowhere, and offer these magical goods to heroes readily. If a devil's contract is broken, whoever broke the contract immediately takes d666 damage, and if they die from this damage, their soul is forced into permanent service to whoever they wronged.
Strangest to the people of the prime material plane, though, is Devil society's obsession with fishing. Every contract with a devil includes a magical fishing rod for 'free', and every devil is an expert fisherman (if they roll to fish, they add +10 to the roll). No one knows for certain why devils are so obsessed with fishing, but if you want to impress a devil, show them your aptitude for fishing.
Their Fisher of Souls ability is very strong - be sure to give your heroes a chance to learn about it so they can plan accordingly.
You gain a +10 bonus to any dice roll involving fishing. If a creature with a soul dies near you, once per round you can claim its soul to restore d666 HP.
Lvl 1 small
You have formed a pact with a creature, and whenever that creature is hurt, you may interpose and lower the damage by 5 if you are within Range: 3.
- Sting.1d10+4
On damage: Target is Poisoned until they take an action.
These imps are devils bound to some other creature, such as a Hag, Dragon, Noble, Vampire, or really any baddy you can think of. They are evil though, so they probably aren't serving a Unicorn.
Lvl 2 small
You are invisible until you attack. You can become invisible again if you take a turn and do not attack.
- Sting.4d4
On damage: Poisoned for three actions
Imps are the weakest of devils, and are stronger when free than bound by a contract. Despite this, they seek contracts, and will not be free long. They are willing to offer healing potions, simple +1 weapons, gemstones worth 100 gold that reek of evil magic, or their service as a familiar in exchange for evil deeds (often a humanoid soul once a month, a fish as offering every week, or a specific person or creature murdered).
Lvl 3
At the beginning of your turn, pick a creature. If they remain in your sight, they cannot cast spells and lose 1 MP at the end of their turn.
- •Eye Blast (x2).1d2+5
(Range: 12).
- •Emergency Escape (1/day).
Teleport to a spot you can see within Range: 30
Ever-Watching Devils are a low-tier devil that look like a basketball with four crustacean eye stalks. They are encased in a hard carapace that protect them from attacks.
These devils do not offer themselves as familiars, but have many imps in their service they can offer, have a weak ability to see the future (they can see one event in the next 24 hours) and will offer this information in exchange for contracts, and if they really want something, they can offer one of their eye stalks (Works as a wand that you can cast any cantrip through, and that cantrip will deal an additional 1d2+5 damage).
Ever-Watching Devils use their future sight to create nearly undetectable nomadic devils. If one of them is in charge of one of these groups, they have 20-30 imps under their control that they send to nearby towns to collect contracts.