In Multiplayer formats it grabs something from each of your opponents, so not only do you take away their blockers, or similar, you then get multiple hasty annihilators for only 7 mana
Brudiclad, Telchor Engineer turn all your tokens into massive threats
Not only does Brago really want to bounce flyers so he can get in for combat damage, you can also use one of the targets of the Expertise to aim at your own artifact or creature with CMC 4 or less, and cast it as the Expertise resolves in order to repeat an ETB effect
Mikokoro, Center of the Sea Mikokoro, Center of the Sea is fine in group hug of the Kami of the Crescent Moon variety
Its a bubble, and it will burst, but the concern is just how much harm it will have done by that point
Sets released before May keep their original pricing