Glass Casket

Cheap enough to answer a creature before it attacks, which is what separates this from most of white's premium removal. The line of enters-the-battlefield exile answers (Journey to Nowhere, Banishing Light, Oblivion Ring) either costs more, catches everything at the price of being easier to unravel, or leaves the body around in some form. This exiles outright, ignores indestructible, regeneration, and toughness, and comes down for two, all in exchange for accepting the mana value 3 or less ceiling as its cost. The restriction is deliberate: it locks the card out of the biggest threats, but the early game is exactly where a white deck bleeds, and this catches all of it. Being an artifact rather than an enchantment is the quiet wrinkle, since it changes which colors and which removal can dismantle it after the fact. That matters because of the exile-until-it-leaves clause, the standard downside on this kind of effect: destroy the Casket and the creature returns, occasionally re-firing an enters-the-battlefield trigger for its controller. The trade is legible in both directions. You get outright removal at a rate usually reserved for spells that only tap, only hit attackers, or only bounce, and you pay for it by conceding the top end and by handing an opponent a way to get their creature back. For everything below the ceiling, few white answers are this efficient or this hard to play around.