Terms of Use

Last updated: August 16, 2026

1. Agreement

These Terms govern your use of Arbiters Grimoire ("the service", "we", "us") at arbitersgrimoire.com. By registering an account or using the service, you agree to them. If you don't agree, don't use the service. How we handle your data is covered separately in our Privacy Policy, which forms part of these Terms.

2. Who may use it

You must be at least 13 years old, and old enough where you live to enter into a contract and to authorise the payments involved. If you're using the service on behalf of an organisation, you confirm you're allowed to bind it to these Terms. Registration is open and accounts are active as soon as you create one, but we may suspend or close an account that breaches these Terms.

3. Your account

• Keep your password to yourself. You're responsible for what happens under your account, so tell us promptly at privacy@arbitersgrimoire.com if you think someone else has access.
• One account per person. Accounts are personal and may not be shared, sold, transferred, or pooled between people.
• Give us an email address you actually control. It's how we'd reach you about your account, and it's the address we verify data requests against.
• You can change your display name and password, and cancel, from the Account page at any time.

4. What the Arbiter's answers are, and aren't

This is the most important section on the page, so it's the plainest.

• The Arbiter is an AI assistant, not a judge and not an oracle. It reasons over the Comprehensive Rules and official card data, and it cites the rules it relies on so you can check its work. It can still be wrong, incomplete, or out of date.
• Verify anything that matters. Every ruling cites specific rule numbers precisely so you can read the source yourself. Treat the citation as the authority, not the summary.
• At sanctioned play, the head judge decides. Nothing the Arbiter says overrides a judge's ruling, tournament policy, or the official rules documents published by Wizards of the Coast.
• Card data and rules text can lag. We refresh from official sources, but a very recent set, errata, or banned-list update may not be reflected yet.
• Deck Builder output is a suggestion, not a legality guarantee. Check your decklist against the current banned and restricted lists for your format before you register it.

In short: use the Arbiter to learn, and to settle kitchen-table arguments faster. Don't use it as your sole authority in a match with stakes.

5. Acceptable use

You agree not to:

• Scrape, crawl, bulk-download or systematically extract the service, its rules data, or its answers, whether by hand or by automated means, and not to resell, redistribute, or build a competing service from them.
• Share, rent, or resell your account or your access, or use one account to serve several people.
• Use the service through automated clients, or in ways designed to exhaust our capacity or our API budget.
• Work around rate limits, the subscription or credit gate, the monthly spend limit, or the credit balance cap.
• Try to make the model ignore its instructions, reveal its system prompt, or answer outside Magic: The Gathering. The service is scoped to MTG rules deliberately, and off-topic requests are refused.
• Probe, scan, or test the security of the service, or access accounts, data, or systems that aren't yours.
• Submit unlawful content, or anything infringing someone else's rights.
• Use the service to develop a competing product, or to train another machine-learning model.

We may rate-limit, suspend, or close accounts that do these things. Where the breach is clear and serious, we may act without notice.

6. Subscription, credits and payment

Paid access has two parts: a $5/month subscription that opens the Arbiter and the Deck Builder, and prepaid usage credits that pay for the AI's actual work. Both run through Stripe; we never see or store your card details.

The rest of the service needs only an account, not a subscription: the Rulebook, and the rulings and decks you have already saved, stay available to you whether or not you are currently subscribed.

• Free trial. New accounts get a 7-day trial. It covers the subscription side only, so using the Arbiter still requires credits. Cancel before the trial ends and you're never charged.
• Subscription. $5 per month, charged in advance, renewing automatically until you cancel. Renewal is handled by Stripe using the payment method you gave it.
• Credits are sold in $5, $10 and $20 packs, and a pack credits its face value. Each request deducts the underlying AI cost plus a margin covering payment fees and the rules context retrieved for your question, so credits are consumed somewhat faster than raw provider cost. Your balance and every deduction are itemised on the Account page.
• Credits never expire while your account is open.
• $20 balance cap. No account may hold more than $20 in credits at a time. Purchases that would exceed it are refused, and the relevant buttons are disabled. Spend some and you can top up again.
• Monthly spend limit. Every account has one, covering the calendar month and resetting on the 1st. It starts out matching your balance when you first buy credits, and only you can change it. Buying more credits never raises it.
• Buying credits requires an active, non-cancelled subscription or trial. We won't sell you credits you can't use.
• Prices may change. We'll give notice in the app first, and a change will never apply to a period you've already paid for. Credits you already hold keep their value.
• Taxes, where any apply to you, are your responsibility unless we're required to collect them.

7. Refunds and cancellation

• Usage credits are non-refundable. Once bought, they can't be exchanged back for money - the AI work they pay for is billed to us the moment a question is answered. The $20 cap exists precisely so this can never be a large sum, and credits never expire, so nothing pressures you to spend them.
• Cancelling never cuts your access short. Cancel and you keep access to the end of what you already have: the remainder of your trial, or the billing period you've already paid for. Your credits stay spendable for that whole time.
• Subscription payments already made are not refunded, because cancelling leaves you with the access you paid for rather than ending it early.
• Cancelling is reversible. Use Resume on the Account page any time before your access actually ends.
• Deleting your account forfeits any remaining balance. Spend it first if you want the value.
• If something goes wrong on our side - you're charged in error, or a fault of ours consumes your credits - tell us at privacy@arbitersgrimoire.com and we'll put it right, by restoring credits or refunding, as appropriate.

None of this limits rights you have under the consumer-protection laws where you live, or under your card issuer's rules. Where those give you a right to a refund, they take precedence over this section.

8. Availability

We aim to keep the service running, but we don't promise uninterrupted availability. It may be unavailable for maintenance, upstream provider outages, or reasons beyond our control. Features may change, and beta features - the Deck Builder is currently one - may change substantially or be withdrawn. If we discontinue the service entirely, we'll give reasonable notice and a chance to spend what you have.

9. Intellectual property

• Ours: the software, the design, and the way the service assembles and presents rules material. These Terms grant you a personal, non-transferable, revocable licence to use the service, and nothing more.
• Yours: the questions and decklists you submit remain yours. You grant us only the licence needed to run the service - to process your input, send it to our AI provider for an answer, and store your recent conversations so you can return to them. We don't use your content to train models, and we don't publish it.
• Answers: use the rulings the service produces however you like. Given section 4, please don't present them as official rulings.
• Third-party material: the Comprehensive Rules, card names, card text and related material belong to their respective owners; we reproduce them for reference and rules explanation.

10. Not affiliated with Wizards of the Coast

Arbiters Grimoire is unofficial fan-made software. It is not produced, endorsed, supported, or affiliated with Wizards of the Coast LLC or Hasbro. Magic: The Gathering, the Comprehensive Rules, card names and card text are property of Wizards of the Coast. Card data comes from Scryfall. For official rulings and tournament policy, go to Wizards' own published documents.

11. Suspension and termination

• You may cancel your subscription or ask us to delete your account at any time. Deletion removes your profile, sessions, conversations, and usage and credit history, and cannot be undone.
• We may suspend or terminate an account that breaches these Terms, that we're required to act on by law, or that presents a security or abuse risk. Where circumstances allow, we'll explain why and give you a chance to respond.
• If we terminate your account for something other than a breach by you, we'll refund the unused portion of your current subscription period. Credits remain non-refundable, per section 7.
• Sections 4, 5, 7, 9, 12 and 13 survive termination.

12. Disclaimers and liability

The service is provided "as is" and "as available", without warranties of any kind, express or implied, including fitness for a particular purpose and non-infringement. We don't warrant that the Arbiter's answers are accurate, complete, or current - see section 4.

To the fullest extent the law allows, we are not liable for indirect, incidental or consequential losses, or for lost profits, lost data, or losses arising from a match, tournament, or purchase decision made on the basis of an answer from the service. Our total liability for any claim relating to the service is limited to the greater of what you paid us in the twelve months before the claim, or $50.

Some places don't allow the exclusion of certain warranties or liabilities. Where that's so, the exclusions above apply only as far as the law permits, and nothing here limits liability for fraud, or for death or personal injury caused by negligence.

13. Changes to these Terms

We may update these Terms. The date at the top of the page always reflects the current version. For changes that materially affect you - pricing, refund terms, or what you're permitted to do - we'll give notice in the app before they take effect, and continuing to use the service afterwards means you accept them. If you don't, cancel; and where a change affects a period you've already paid for, contact us.

14. Contact

Questions about these Terms, billing problems, or anything that looks wrong: privacy@arbitersgrimoire.com.