This gives you a second chance to play even more cards in a turn, overwhelming your opponent with the sheer number of cards and resources available to you
One day even Post Malone will come along and buy some cards on Mage - if you don't know who Post Malone is, he is a rapper, and also the guy that paid 1.57m for The One Ring
Not only that, but any time you exert this card in play, you get to draw a card
You get to suspend ridiculously mana-intensive cards and let your tablemates worry about what they'll do when those spells eventually get cast
Printed in Japanese with a nice, colorful finish, the Master Key Prize card is known to only have 36 (authentic) in circulation
Everybody Lives effectively guarantees that the board state will remain just the way it is