Cornered Market

No choose-a-name clause appears anywhere in the text, and that omission is the entire mechanism. The static effect reads every nontoken permanent on the battlefield and turns each one's name into a prohibition: while a permanent is in play, no one can cast a spell sharing its name, and no one can play a nonbasic land sharing its name. The lock follows whatever is already on the table, so the player who develops first dictates which names go dead, and the symmetry printed in the text becomes a fiction in practice. Resolve your copy of a staple permanent and every other copy in every hand turns to a brick, including the ones an opponent was counting on. It hits both halves of acquisition, the cast and the land drop, so a single resolved dual land or efficient creature can strand a chunk of a hand it overlaps with. That overlap is the whole identity. Against a field of diverse threats it does almost nothing, since nobody is racing to deploy the same card twice; against a mirror of shared staples and shared fixing it can shut off half a hand. This is a stax piece whose ceiling is set by how much the table converges on the same permanents, scaling with redundancy on the battlefield rather than in any one deck. A lock that depends on the table to agree on its win conditions has never found a permanent home of its own.