My guess is that fully modeling MtG's rules in Datalog would take a lot more work, because MtG's rules are a lot more complex. Looking through the source for one of the freely-available game engines like https://github.com/magefree/mage would probably be more informative, though.

EDIT: I found an old project working on implementing the MtG rules in Prolog: https://github.com/stassa/Gleemin. It's definitely more concise than XMage's Java, but you can still get an idea of how much work it would take, especially since that project notes some pretty significant limitations that it didn't get to.