Curse of Marit Lage
The enter trigger taps every Island on the table, and the static clause holds them down: a manabase built on the Island subtype stops untapping the moment this resolves and stays frozen until the enchantment leaves. The effect reads symmetrical (it hits any Island, regardless of who controls it), but the caster breaks that symmetry in deckbuilding, simply by running no Islands and letting the opponent absorb the full freeze. Even on the turn it lands, the blue player loses access to whatever they were holding up. That precision is also its ceiling: against a deck whose mana does not carry the Island type, it draws blank, a narrow answer that is devastating against the right manabase and dead against everything else. Crucially, the lock keys on the subtype itself, not on whether the land is basic, so duals like Tundra and Watery Grave fall to the same clause; the way around it is to run no Islands at all, not to swap basics for nonbasics. The flavor sits right on top of the mechanic, the Marit Lage cold snap rendered as Islands that never thaw. What dates it is the target. Punishing a land subtype rather than nonbasic mana or color identity is a knob Wizards mostly retired, and the card now marks an early, blunt era of color hate before the screws got more precise.
