Without the Brooms, it's nothing special, but with them, it's a standout card that costs only two ink
Getting any two lands like Field of the Dead or Valakut, the Molten Pinnacle enables powerful strategies
The whenever attacks is really nice, life gain and card draw
Its generally expected that any future unbans become a Game Changer as theyre unbanned, and future bans are likely to be added to the Game Changer list first
Aside from flavor, you can interfere with opponents who are using typal effects like Distant Melody or Coat of Arms for value by changing their creatures to other things
As for Decimator, uncounterable on your Overrun is very nice against the blue decks