Olivia's Midnight Ambush
Two spells share one card here, and the number between them is enormous: -2/-2 by day, -13/-13 by night. The small mode is an honest combat trick that trades with early creatures and shrinks a blocker out of profitable combat. The night mode is not a bigger trick but a different card entirely, erasing nearly anything with a printed toughness. Because it kills by dropping toughness to zero rather than dealing damage, indestructibility offers no protection; the creature simply ceases to have enough toughness to exist. The catch is that you do not control the switch. Whether it is night depends on the board's rhythm of casting and holding back across the whole table, so the value of this instant lives outside your own hand. Holding it for the kill means trusting the cycle to turn before the game does; taking the -2/-2 now means accepting a modest answer because tempo will not wait. Reading that dynamic well is the entire skill: knowing when the sky is about to flip, and when patience is just a slow loss with a two-mana instant stranded in hand. Most cheap black removal does the same thing every game, and its floor is its ceiling; this one hands you a guaranteed small effect chained to a conditional overwhelming one, and asks you to gamble on which the night owes you.
