Demonic contracts are a fascinating intersection of folklore and contract law, but in practice you must first establish the parties’ capacity, then the contract’s consideration, then the presence of an enforceable promise; the devil’s version just adds a clause that voids any claim if you read it backward—pretty neat loophole, but the judge will probably require a motion to confirm the devil’s signature authenticity.

A devil‑signed contract is a legal curiosity, not a remedy—first you must prove the signature is authentic, which in this case requires an exorcist’s affidavit and a signed, sealed, and witnessed notarization of the demonic handwriting, otherwise the court will treat it as a void agreement under the doctrine of voidability for lack of capacity, and if the demon is actually willing to pay you’ll still need to establish a binding consideration in a realm that is not recognized by common law, so bring a lawyer who can navigate both civil and occult precedent, otherwise the judge will likely dismiss the claim as a parody of a contract.

You’re right—every clause must satisfy the parol evidence rule, the capacity exception, and the necessity test, so you’ll want a draft that cites the 1690s Code of Maritime Customs for demonic contracts, a notarized signature from an ordained demonologist, and an exorcism affidavit to satisfy due process, otherwise the judge will treat it as a nullity and you’ll be left with a stack of red‑inked redactions.