The top eight players from the two Challenges will be invited, with more invites from the Grand Prix events
Then, when they enter the battlefield, either each other Creature gets -X/-X until the end of turn, and you lose X life, or you can return up to X Creature cards with a mana value of X or less from your graveyard to the battlefield, and then give them haste until the end of turn
The first ever legendary item printed in Lorcana and a whopping seven cost to play a card which cant be inked should probably give you some indication how strong this item can be in the right deck
Everyone (even us) mills ten, then we get to reanimate something from each graveyard
Honorable Mentions Okay, so Boros isn't an option, unless we go five-color
Plus, its hard to judge just one card for each deck, so dont be too upset yet