$12 is a lot for this, but for some decks its essential
Ayli, Eternal Pilgrim has a nice lifegain sacrifice ability, and once youve gained enough life, it has a great aristocrat removal ability
Gurmag Angler seems incredibly easy to cast as early as Turn 2 for the deck, thanks to Street Wraith, fetchlands, Burning Inquiry, Faithless Looting, and Cathartic Reunion
This is useful for when you want to get something back when Jirachi dies
C(N K, n k) counts the number of ways to fill the remaining n k slots in the sample with non-successes
The number of times Ive sunk a bunch of mana into getting The Reaver Cleaver attached to a creature, only to swing in, generate a ton of Treasure, and play out another full turns worth of spells is innumerable