pokemon card regice ex - Regirock-EX (43/124) - XY Fates Collide done to Regice ex by the Attacking Pokémon Regice Ex | eBay

But by default the game trusts you to know what youre doing and wont slow you down unless you ask it to

Each card on the list has a specific reason for being illegal

A Threatening Board is a Perfect Board The last big question that we still have to answer is how to figure out what that perfect board actually looks like

It seems kind of silly and a way to get someone that worked on the idea a little more attention, but the cards can also have a very interesting quality as they make everyone reveal their hand and turn their deck upside down so that anyone looking can see just what card is going to be pulled next

You can do something similar with Warp cards and a sacrifice outlet

--- These were the most expensive cards in the latest Pokemon TCG expansion Rebel Clash