Doesn't having all 3 levels on one card sort of undermine the point of the cards, in that you could only use monsters you have models for? It essentially just replaces the 2 dice rolls and a table with 1 dice roll and a card draw but is still just using the exact same table and producing the same result.
Also if you have monster stats on the cards you'd want to keep them out of the deck for reference which would then preclude the other levels on the card from appearing whilst that card is in use.
Yes indeed, both fair points.
I guess then that the "simplest" solution would be to just draw up your own table with monsters from your own collection (i.e., that you have models for). Saves the faff of having make any cards then as well, and still achieves the same result.
Also, just noting that most card decks come as 54-card packs, so three decks of 20 will leave you with an odd number. Unless you also make your own cards, of course.