Mox Diamond

The genius and the flaw of the Power Nine fixed-mana model was that the original Moxen made mana from nothing: zero cost, zero downside. This card is the design correction, the first serious attempt to recapture that free-acceleration ceiling with the cost baked into a replacement effect rather than the mana cost. The discard-a-land clause does the balancing work: you are not paying mana for the artifact, you are paying a land, which means the acceleration is real only if you have a land you would rather convert into a permanent, color-flexible mana source. That trade has a sharp edge. It does nothing on a landless hand, and the land it eats is one you might otherwise have played, so the card rewards a hand flush with lands and short on early plays: the converted land turns dead surplus into a colorless-to-any ramp piece without costing you tempo. The replacement wording (it either enters or goes to the graveyard, no middle state) closes off the obvious abuse: there is no version where you keep both the land and the Mox, and no window to fizzle the discard and still bank the artifact. What it preserves from its ancestors is the thing that made them broken in the first place: a turn-zero-feeling permanent that taps for any color and never asks for mana again. The land it eats is the leash, and the leash is the entire reason it is legal anywhere the originals are not.