The candidate of course has to know all the details of all the cards or just be capable of studying to learn all the details. Interestingly, Kobayashi explains that the game designers make a point of never hiring pro players

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There is no point in removing the Sundial in response to its activation, it wont alter the flow of the nearest future
This gives them a lot of versatility and stops them from being dead draws against decks where their specific defensive ability isnt relevant
But here we won't be worrying too much about variants, we'll be looking at the regular cards you can find outside of collector boosters
Until recently they weren't even advertised, being a surprise extra for the buyer to discover