Mox Pearl

Broken in its purest form: pay nothing, tap for a colored mana, no drawback, no upkeep, no life loss, no discard, no restriction on when or how. Every fast-mana artifact in the decades since has carried back what the Moxen left off: Chrome Mox exiles a card, Mox Opal demands metalcraft, Mox Amber needs a legendary on the battlefield, Mox Diamond eats a land. The original asks for nothing. The structural problem is not the mana acceleration itself but the absence of a cost that scales with the advantage gained; a turn-one Mox Pearl into a two-drop is not a tempo trade, it is a free card whose only opportunity cost was drawing it. That is why the Power Nine sit on the Vintage restricted list and why Reserved List status has frozen the print run in the mid-nineties. The white member of the cycle is the least storied of the five (white's early-game ceiling never matched blue's or black's), but the design lesson is identical across all of them: a free permanent that manufactures a resource the moment it lands is the original sin of Magic's mana system, and thirty years of card design has been spent learning how to flirt with it without repeating it.