When used in-game, the Masters Key card text (as translated from Japanese) allows the player to draw a card, before flipping a coin
Tifa, Martial Artist Tifa, Martial Artist makes it hurt, a 7/7 trampler just needs to squeak one point of damage in, and you'll untap all your creatures including those you stationed with, mana dorks and pingers
Another type of large Pokemon cards, which can be categorized as a separate type from the jumbo cards are the box toppers, which are very hard to find
These are three pretty popular archetypes and so this has potential to really take off
Legendary Collection cards can be identified by their set symbol of a medallion just beneath the lower right corner of the image
The bulbapedia states that only 5250 were awarded, with 200 given to the illustration winners and one pack to 5000 other entry winners