Mana Web

A punishment card built on a trigger nobody can sidestep entirely: the moment an opponent taps a land for mana, this snaps shut every other land they control that could produce the same type. Because it triggers on the act of tapping rather than on the spell itself, the lockdown follows fast on the heels of that first tap. The opponent's recourse is to respond to the trigger by floating mana, tapping their remaining matching lands in the same step so they at least get value before everything locks. That is the real squeeze: Mana Web does not steal their mana so much as collapse their tempo, forcing all of a turn's land use into a single window and denying the ordinary luxury of casting a spell now and holding mana up for later. Against a mono-color manabase the effect is brutal, since one tap implicates the entire field of like lands. The classic pairing is with effects that already cripple untap steps, like Winter Orb, where the opponent's pool of available mana is small to begin with and being unable to ration it across phases turns a slow grind into a vise. The dependence on the opponent acting first is the catch: it sits inert against a player content to leave mana open and only ever responds to a tap that has already happened. That conditional, prison-warden shape is the same stax design language the old white-and-artifact lock decks were built on, and this is one of its sharper teeth because it costs the controller nothing on an empty board.