Both cards are holofoil and shadowless (just like Mewtwo,) and both were rated a perfect 10 by the PSA
Providing two mana types on a single land that comes into play untapped, and has both basic land types, make the original duals the best in the game, and of course its the blue ones that are most desired
I am generally against Block formats since they are less popular and oftentimes worse than existing Worlds formats, however, Black & White block adds only 2 more sets to the 2013 Worlds format
Defiler of Vigor Theres a whole cycle of Defilers in the set, which allow you to pay Phyrexian mana for their color of mana for any spell, and thats pretty crazy
One significant detail that may disappoint fans is that trading functionality will not be not be supported in the new game, meaning that users will only be able to add new cards to their accounts by scanning in QR codes directly or by using in-game currency to purchase new digital cards