Cannot attack unless you control a Fusion Monster
According to this theory, Masterpieces generate more excitement and direct participation for pack-crackers than Standard players, but everyone wins, since Constructed becomes cheaper on the back of increased Limited participation
These are "secret rare" cards
Ideally, you're giving your opponents horrible cards such as Boldwyr HeavyweightsBoldwyr Heavyweights, Eater of DaysEater of Days, and LevelerLeveler
There is also an ability hidden at the bottom that I have gotten people with
This will let you use Xanathar's ability at least two more times, targeting multiple opponents, letting you steal from their library and shut down their spells