Its an excellent asset to any Purple decks
Rarity symbols are important because they help determine a cards value and desirability
"Mill" is a colloquial term that originates from the card Millstone, used here to mean "putting the top cards of a player's library into his or her graveyard." For example, you could say, "In the finals of the Pro Tour Qualifier, Herbert cast Tome Scour to mill away my final five cards, dashing my chances of playing on the Pro Tour." There are many players who will play with Tome Scour in their decks
However, one look at that fiery red artwork shows why this card occupies such a high spot on the list of the most valuable Inferno X cards
Charlotte Perospero trashing a card to activate his main effect, but will ramp back 1 Don, so we wont fall behind by activating the Leader effect, and well get to draw a card
The trailer does show us three Mega Evolution Pokmon cards from the upcoming set, however, so we know exactly how this mechanic works