Revelation

World is a Legends-era supertype built around a single rule: the battlefield holds just one world permanent at any moment, and a fresh one entering puts the older world permanents into their owners' graveyards. That restriction is the entire design discipline here. For one green mana, all players play with open hands, a symmetric information-flip that wrecks bluffing, reveals counterspell density, and turns every draw step into a public event. The symmetry is the cost: green, the color that historically wants to deploy threats and force the opponent to have an answer, benefits more from seeing the grip than the color trying to hide a hand of interaction. The world rule is the pressure valve. Without it, a one-mana global hand-reveal would be an oppressive lock piece stacked across an entire table; with it, the effect is contestable, displaceable by any other world enchantment, and self-limiting in a way modern hand-reveal designs (Telepathy and the various peek effects) achieved instead through color-pie restriction and higher rates. The card preserves a design moment when the rules engine itself, rather than mana cost and color identity, did the work of keeping a sharp effect in check. Most of what Revelation does has since been redistributed into blue at sorcery speed and higher cost; the green, one-mana, world-enchantment version is the road not taken.