I'm actually working on this right now! https://chiplis.com/ironsmith

It's a parser + (de)compiler and rules engine which I'm trying to get to 100% coverage over all Standard/Modern/Vintage/Commander legal cards. About 23000 of them are partially supported, while 15k currently work in full (~3k more than what MTGA currently supports, IIRC). It also allows for P2P 4-way multiplayer which Arena unfortunately does not :/

This is seriously impressive!!

What are you planning on doing with this? Where should I follow along?

The Arena card engine is based on CLIPS [1] and not modern LLM-based tools. Magic cards are written in a very constrained language (usually called "card templating") that lends itself very well to machine-parseability.

[1]: https://www.clipsrules.net/

There was an era about 10-15 years long where that was true but modern cards often fall back on very loose language that they tighten up with rulings prior or sometimes after release. See the language behind the "Prepared" key word in the newest set for a striking example.

I don't think Prepared is ambiguous at all. It has its meaning defined in the CR (722) and every card that uses it has either a clear trigger condition or the "enters prepared" replacement effect. It's just a new designation and there are plenty of those already, including ones that are 10+ years old (Renowned, Monstrous, Level Up).

Well there was a huge discussion on what it means amongst judges. On plain reading it does not do what it states it does. Start just with the phrase "its spell" - those words are entirely undefined until getting into the rulings, and don't mean what they mean in other contexts. It makes no mention of the prior rules that it sort of hacks into this either.

I have no idea what rule 722 has to do with prepared.

I'm a judge and have seen barely any discussion around Prepared (mostly just clarification around the interaction with.

Rule 722 is the rule for "Preparation Cards", so I fail to see how it could not be relevant.

The text "its spell" only occur in reminder text, which is not rules text and would not be included in template language.

Ah, I have I guess an old version of the CR downloaded from when I was a judge and TO where rule section 722 is "Controlling Another Player," weird reorganization there.

Are you active in judge forums or social media at all? Huge threads on prepared with these arguments (I didn't come up with the idea as I now longer play or judge).

Regardless of whether you think this one example is confusing, WOTC came out a few years back and said they were sacrificing clarity for more natural language as a development goal and it's clearly noticeable in the cards.

Sorry, throwing out a text because its reminder text is a cop-out, that's the only way 99%+ of players are going to interact with the rules. The rule makes sense when demonstrated but from a logical step-by-step when following what it says on the actual cards it does not actually function in a way that conforms to the way it is supposed to work.

I'm specifically talking about the use case of "can we use natural-language tools to parse oracle text and produce functioning game objects in Arena". For that use case, it's completely sensible to look at the actual rules text and not reminder text.

Looking back further, there was confusion during preview season when people were looking at "fake/leaked" mockups that had incorrect text on them, but this also isn't a problem for the issue of "WotC themselves writing systems that can parse card text".

I think that level of ambiguity would be fairly easy to tighten up using the CLIPS system that was previously discussed. It isn't bug-proof and has needed manual tune-ups before but it's much more "hardened" than what we think of as AI now with LLM-powered tools.

As others have said, there is an actual concrete system for translating card text into rules, and it's not an LLM (which would be a disaster).

I assume the wording in this letter is referring to using LLMs to generate slop as creative assets like images and music.