Gitaxian Probe + Mishra's Bauble Let's put it this way: A cantrip that you can pay for with life rather than mana, and tells you what your foe's up to, is so fundamentally broken that Gitaxian Probe is banned in Modern and Legacy, and it's also restricted in Vintage, where it's no stranger to top-tier decks
I have tested versions with both (3 Switch and 2 Float Stone) that have done well, but just like the above question, there is no wrong answer
With The Lost Caverns of Ixalan, a ton of new, powerful cards are entering into all formats
Here is a brief summary of how the rule would work: If a player has no Basic Pokmon, they reveal their hand to their opponent and go through the normal mulligan procedure but their opponent does not get to draw any extra cards
They seem to have managed it
Its site offers built-in price-tracking tools, with the transaction history for each card