Bone Devil

A bone devil "on the party's side" is a contract, not a friendship. It has been hired, summoned, or forced into temporary service, and the agreement is binding only as long as the wording holds. Sell the contract at the table. Read the relevant clause aloud when the devil acts, and have it twist any vague instruction toward Lawful Evil ends. Players who say "deal with the guards" find the guards' families dealt with too.

In combat under contract, the bone devil is a precise asset. Send it to the back rank to Infernal Sting the enemy healer, since the no-healing rider on Poisoned is exactly what the party would want against a hostile cleric. The 40 ft. fly speed lets it skip past terrain the party has to walk through. Magic Resistance and Immunity to Fire and Poison make it the right tool for traversing a fire elemental's lair or eating a poison gas trap on the party's behalf. Deception +7 means it lies smoothly, including to the party.

The exit is the price. The devil will collect the agreed payment the moment the contract is fulfilled, and any ambiguity in the wording is collected as a favor owed. If the party tries to extend the arrangement, the devil renegotiates from a stronger position. If they try to dismiss it early, it interprets that as breach and walks free of all restrictions.

Have the devil say goodbye in writing. A scroll left behind with the contract marked "fulfilled" and one line in red is more menacing than any threat said aloud.

A bone devil is the middle management of Hell, and it fights like a foreman who knows exactly what every tool in the box can do. It opens at range whenever possible, talks first when it has leverage, and never picks a fight it can postpone for a better one. Telepathy 120 ft. and Infernal mean it can negotiate from across the room before any character has a chance to roll initiative.

Once combat starts, the Multiattack is the centerpiece: two Claws at +8 for 13 each plus one Infernal Sting at +8 for 15 piercing and 18 poison, with the Poisoned condition blocking healing until the start of the devil's next turn. Pick the cleric or the bard. A healer who can't heal is a healer the party can't recover from, and the bone devil's 161 HP and AC 16 mean the fight will run several rounds. Use the 40 ft. fly speed to stay just above the reach of the front line and force the melee to chase, then drop in for a full Multiattack and lift away on the next turn if the dice go badly. Magic Resistance turns most save-or-suck spells into a 50/50, so don't let the table assume a single Hold Monster ends the encounter.

Bone devils retreat. They are bureaucrats with knives. Once Bloodied or once an objective is achieved, the devil will withdraw via flight or by parley, often offering information on a rival as the price of disengagement. Diabolical Restoration means death simply puts it back in the Nine Hells with a grudge, so a fled bone devil is a recurring NPC whether the party wanted one or not.

When the devil first speaks, give it a name and a contract. The PC who killed its last vessel is on a list, and the devil should reference that fact before the first claw lands.