Humble the Brute

The power-4-or-greater clause is the whole architecture: removal that refuses to touch the small stuff. White has always had clean unconditional kill spells; this one trades universality for a baked-in floor, then pays you back for accepting the restriction with a Clue. The math behind that trade is deliberate. Five mana to answer only genuine threats is a soft rate on its own, so the Investigate keyword action widens the payoff: because it resolves as part of the spell rather than as a separate trigger, killing something big enough to legally target also banks a deferred card in the same breath, turning a narrow answer into a source of long-game advantage. The card never pretends the exchange is even on tempo. Five mana to kill one creature is a real cost, and the Clue does nothing to recoup it; what it does is convert that cost into raw cards, betting that a grinding white deck cares more about attrition than about the turn it fell behind. That is the design move worth noticing: rather than capping the ceiling, the restriction is bundled with a consolation engine, so a spell that can only be cast against real threats still digs into the rest of your deck once it fires. Because it is an instant, a defensive deck can leave mana open through combat and the opponent's turn, answering the haymaker the moment it lands, then cashing the Clue once the board has stabilized.