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
There are about 70 Magic cards with this mechanic, and in this article we'll rank the 31 best among them
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
But here's the kicker: you can only choose each option once per turn, so the order matters
One mana one for one discard isn't exciting when you gain little information from it and have no choice in what to take
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