Sol Ring

One mana invested, two colorless returned the instant it resolves: the rock pays for itself the turn it lands and nets two mana every turn after. That profit margin is the whole story, and no acceleration artifact since has matched it without friction bolted on. Mana Vault asks for a payment in untap steps and life; Grim Monolith stays tapped; Mox Diamond demands a card pitched to it. This one carries no such tax, which is precisely why it has been restricted from the start, legal but capped at a single copy in Vintage and banned outright from the shallower card pools where even one copy proved too much. The colorless output is part of the discipline: it accelerates any deck regardless of color, which makes it universally desirable and impossible to wall behind a color commitment. What the card represents is ramp stripped to its bones: no conditions, no clock, no cost beyond the mana that cast it. Every artifact accelerant printed in the thirty years since has been a Sol Ring with a tax attached to make it printable, which is also why it became the unofficial centerpiece of multiplayer tables: a card so universally correct that Commander stopped pretending anyone would cut it and started printing it into precons by default.