Choke

Blue's whole reactive posture depends on Islands staying available: counterspells held up across turns, draw spells cast on the opponent's end step, tempo decks that float untapped mana to threaten interaction. Choke severs that line at the root. It does not stop an Island from being tapped for mana; it stops the Island from coming back, so a blue player can spend their lands once and then watch a hand of instants rot. That is the design's whole engine: it costs almost nothing to the green deck deploying it and everything to the deck whose plan assumes mana renews each turn. The brutal slope comes with a sharp edge of narrowness. Against an opponent running no Islands, the enchantment reads as a blank, so its value sits at near-zero or near-total with almost nothing in between, a binary that few hosers commit to as fully. The card exploits a structural truth about how blue wants to operate: holding mana open is the color's safest-feeling default, and this is precisely where Choke does its damage. The design descends from the old color-pie premise that green and blue are natural antagonists, and that hosing a color should hurt where that color believes it is most secure. Strip the renewable mana and the reactive game plan collapses on its own weight.