Serious collectors are open to spending upwards of $250,000 USD to complete their collection
It had roughly the same number of designs, but fewer copies made, and only a smaller group of testers participated
Other cards revealed in the stream today show the range of powers and potential archetypes available to players, including Fierce Empath, which can help you find huge creatures hiding in your deck, and Runed Halo, which can offer a lot of protection against decks aggressive or tricky decks, and Teferi's Ageless Insight, which will allow players to draw tons of cards (everyone loves to draw cards!)
I wouldn't have an issue if you ran it against me in Pauper Commander since it's a one-of, but your milage may vary
Besides dessicant packs to control humidity, not sure what else to suggest
Mirror Wall Mai Valentines most powerful trap card, Mirror Wall is a continuous trap card that negates an opponents attack and halves the attack of the attacking monster