Riddle of Lightning

Burn that turns your own decklist into the damage roll. The five mana buys an instant-speed bolt whose size is whatever mana value happens to sit on top of your library, which makes the Scry 3 attached to it the entire engine: you see and arrange the top three cards before the reveal locks in the number, so the gamble is one you mostly get to fix in advance. The card never plays as a coin flip, because the setup is baked in; the real constraint is what you put in the deck to begin with. A low-curve build reveals into a one-or-two-damage embarrassment no matter how you sort it, while a deck stacked with expensive payoffs lets the Scry tee up an arbitrarily large hit. The card rewards a steep curve and punishes a flat one in the same motion, asking you to build around the reveal rather than draw into it. Choosing any target rather than just creatures or players keeps it honest against board states a creature-only burn spell ignores, so a fat reveal can erase a planeswalker as readily as it ends a game from across the table. It is a deck-cohesion test wearing a burn spell's clothes, where the cards you decline to run shape the spell as much as the bombs you keep on top.