When you Synchro Summon the Level 8 DARK Dragon, The Crimson King (seen on the left), you can add any card from your Deck to your hand that mentions Red Dragon Archfiend
He's a demon, though, so we also knew it had to be something that would most often be beneficial for you but had the potential to go wrong
Until you invest five mana into it the card is just a 3/2 for 3 which is not at all good
In a meta with less Durant and more traditional decks, here is what I would play: 4 Twins, 3 Professor Oaks New Theory, 3 Professor Juniper, 2 N, 2 Pokgear 3.0
Card offerings are limited as of this writing, but expansions promise to greatly increase the number of available cards
When an effect of a monster your opponent controls is activated that targets 1 Cyberse monster you control (and no other cards) (Quick Effect): You can negate the effects of both that Cyberse monster you control and that opponent's monster until the end of this turn