24 booster packs per box
Depending on your deck, you might also want to look at Clever Concealment, Flawless Maneuver and Cosmic Intervention the latter of which is a lot of fun with fetchlands and mass land destruction, or board wipes when you run a lot of strong EtB effects
Still, on a creature like Laelia, the Blade Reforged this will pull its weight
Conspiracy: Take the Crown Spoilers - August 18th, 2016 The first spoiler for the day is from last nights episode by webcast Magicmics, and is a reprint of Dragonlair Spider, last seen in Planechase (2012) and Commander's Arsenal
Additionally, if it's in a player's opening hand, they are able to start the game with Leyline of Anticipation on the battlefield
Well, lets just say that Mind Twist would likely be the more popular choice, assuming you could only pick one