Barbed Devil

A barbed devil ally needs a contract. Maybe the party signed an infernal pact for one favor. Maybe a tiefling PC's patron lent it as a bodyguard for a single job. Maybe the party rescued a cambion who repaid them with a single hour of a barbed devil's service before the loan expired. Whatever the setup, the devil is here for a fixed term and will read the contract back to anyone who asks.

In combat, the devil grapples whoever the party points at. Claws to lock down, Tail to chip a second target, Barbed Hide to punish anyone who tries to free the captive. It does not heal allies, does not scout, does not hesitate. If the party tells it to capture rather than kill, it complies, but the prisoner will be bleeding from a dozen barb wounds by the time the fight ends. Fire immunity and Magic Resistance keep it standing through most of what the encounter throws at it.

Outside combat, the devil watches and reports. It speaks Infernal and uses telepathy 120 ft., so language isn't a barrier with anyone who shares a tongue or accepts the link. It also has +5 Insight and Deception, which means it will read the party's mood and lie smoothly when it suits it. Trust nothing it volunteers.

When the contract ends, the devil leaves immediately, in sulfurous smoke. If the party tries to renegotiate without offering something specific, it laughs and goes anyway. Have the next devil they meet remember their names.

A barbed devil is the grappler of the lower hells. Its job in any fight is to lock down a frontline PC while the rest of the encounter does the killing. Run it that way: don't open with Hurl Flame from across the room when you could be in melee, dragging the paladin into a corner and bleeding her on Barbed Hide.

Open with Claws if you can reach. The Claws attack is +6 for 2d6+3 piercing, and on a hit a Large or smaller target is Grappled with escape DC 13 from both claws. Then the Tail at +6 for 2d10+3 slashing, reach 10 ft., which the devil can use on someone outside the grapple while still holding the first target. Next round, Barbed Hide does 1d10 piercing automatically to anyone the devil is grappling, and to anyone grappling the devil. That means barbarians who reach in to break the hold also bleed. If melee isn't available, Hurl Flame at +5 for 5d6 fire from 150 ft. is a passable second option, two attacks per Multiattack.

Target priority is the player who can free a grappled ally. Lock down their tank, then concentrate on the cleric or rogue who's about to cast Misty Step or Freedom of Movement. Magic Resistance gives the devil Advantage against spells, so the wizard's first save-or-suck spell will probably bounce. Let the players see that happen. It tells them this thing is built to grind, not to be dispelled.

Barbed devils don't flee. Diabolical Restoration means a death outside the Nine Hells just sends it home, fully healed, with a grudge. It will fight to zero and laugh on the way out. If you want a recurring villain on the cheap, kill one in act one and have it return in act three with the cultist who summoned it both times. The party's win was always temporary; let them learn that.