There are about 70 Magic cards with this mechanic, and in this article we'll rank the 31 best among them
So yes, its about 5-10 times easier to get a nonfoil, and 2-3 times easier to get a foil, depending on if the card would be rare or uncommon
Theres no annihilator, but you do get to draw however many cards you need to have seven in hand when you cast them, so thats cool
Green gets bite spells, black burn spells like Consuming Corruption tend to gain life, and white ones like Hobbit's Sting or Joust Through relate to creatures and combat, for example
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Shadowborn Apostle, Relentless Rats, or even Persistent Petitioners in a Dimir build will all enjoy a one-mana buyback of a limitless amount of their main game piece