In Commander, you are probably running Lathril, Blade of the Elves
With Bruvac in play, any time your opponent mills at least one card, they mill double the amount instead
This leads to more interesting decision-making than the Amonkhet version, which was often just exert to attack, unless I can attack normally. As another nice extension, theres a set of cards where you effectively Exert yourself , getting a huge effect for a low cost, but denying you access to most of your mana next turn
Case configuration: 1 factory sealed case = 12 booster box displays
It was also the first time they'd been taught by someone who looked like them
In formats like Modern or Commander, you can use Necrodominance to draw a massive amount of cards and then simply go to your cleanup step