Current Standard actually has a surprising amount of support for a card like this
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Maybe the real answer is that it should depend on your storage solution
For example, 'Queen of Hearts, Wonderland Empress' has an ability that gives other Villain characters +1 lore whenever it quests
A very general guideline is having at least 40 cycling cards, the more the better
These cards include tutors to find your key cards, the key cards themselves, and any supporting elements to improve your chances of winning