Chromatic Lantern

The reason this became the fixer of choice across gold-piled decks comes down to what it taxes and what it doesn't. Cards like Coalition Relic or Darksteel Ingot give you any color too, but they spend a card slot doing work a land could be doing, capping your rainbow output at the one rock. This pushes the fixing down onto the lands themselves: every basic, every tapland, every utility land you already run becomes a perfect mana source, so the rate scales with how many lands are in play rather than topping out at a single activation. The self-contained final line (the artifact still taps for any color on its own) is the insurance policy: a stray land-destruction effect or a missed land drop doesn't suddenly leave you colorless, because it keeps producing regardless of the board. What makes it durable as a design is that it sidesteps the usual fixing tax entirely. Most any-color sources ask you to pay a premium per activation or accept a slow body that does nothing else; this one converts your existing manabase into rainbow lands and then sits there, demanding nothing but artifact removal to undo. It is the answer to color-screw that asks nothing of your deck except that you have lands, which is why it settled in as the default wherever a four- or five-color pile lives or dies on whether the lands cooperate.