Hour of Defeat

Unconditional creature destruction has been priced down to two mana for most of the game's life, so the four-mana version needs a reason to exist beyond the kill. Here that reason is the surveil rider: destroy any creature outright, then filter the top of your library, either drawing closer to your next threat or seeding a graveyard for whatever wants feeding. The rate is deliberately soft; you pay a premium over the cheaper unconditional answers (Murder, Doom Blade and their kin) and get a small card-selection dividend in return. What makes the effect coherent rather than overcosted is black's long relationship with the graveyard: the color rarely surveils just to dig, it surveils to stock. Binning a creature or a flashback spell off the top can be worth more than the raw removal in a deck built to mine what it discards. Because it is an instant, the surveil resolves on the opponent's turn too, letting you set up a draw or bury a specific card in response to what is developing across the table. It is a workhorse removal spell that trades a share of its efficiency for a sliver of inevitability, aimed at the midrange black decks that would rather answer a creature and improve their next few turns than simply spend the least mana possible.