1999 nintendo gold pokemon cards Pokémon 23K Plated Trading Card - #6 Charizard 1999 NINTENDO CHARIZARD LIMITED EDITION

Unlike other options like Liliana, Dreadhorde General, and Null Profusion, you are likelier to find this in Constructed formats

The popularity of Sakashima of a Thousand Faces is a good indication of how prevalent this spell will end up being

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Unfortunately, you also need 4 of these for Legacy, as it has a unique effect and generates so much mana in the Elves deck

So unless there is some pattern where similar cards appear to be rarer or more common, or the sample size is a lot larger, brute force wont deliver definitive answers (though it is still interesting of course)