Cradle to Grave

The window is the whole card. Black has always paid a premium for unconditional creature kill, and the usual toll is mana, life, or a wait while the threat sits on the board through a turn cycle. This pays the toll in timing instead: it only touches a creature on the turn it entered the battlefield, which makes it a functional counterspell for everything black cannot actually counter. A freshly cast bomb, a token that just hit the board, a flicker target that re-entered: all of them are nonblack newcomers, and all of them die for two mana before they untap. The color restriction is the other half of the rent. Black declining to kill its own is an old discipline, and here it doubles as the reason the spell can be this cheap and this broad against everything else. The timing clause also inverts the usual liability of removal: instead of leaving you a turn behind a threat already in play, it asks you to hold up two mana and answer the threat at the moment it is weakest, before an attack trigger, before haste matters, before the controller has spent anything protecting it. The catch is symmetrical to the strength. Against a creature that resolved last turn, the card is a blank, so its value rides entirely on having open mana into the exact window it was built to punish.