Lithomantic Barrage
Color-hate spells are among the oldest tools in the game, but almost all of them buy their premium rate with a wall: they only hit creatures of the offending color, sit inert against everything else, and rot in hand when the matchup goes wrong. This one splits the difference. Against anything it is a one-mana pinger, enough to snipe a mana dork or shave a loyalty counter off a planeswalker. Against white or blue, that same red mana turns into five damage, which kills nearly every creature those two colors care to field and puts a real dent in a walker. The card never becomes a dead draw: the floor is a modest ping, the ceiling is a color-tuned assassination for the same cost.
The uncounterable clause is what gives it teeth against blue specifically. A one-mana removal spell that resolves through Force of Negation, through any soft counter, through a control shell's whole game plan, is a very different threat than a burn spell that can be answered on the stack. It closes the window a blue deck relies on: you cannot Spell Pierce it, you cannot Daze it, you point it at the tapped-out control player's board and it happens. Against everyone else it is a small pinger with no upside; against the two colors it names, it is a hate card that refuses to be interacted with on its own axis.
