Amnesia

The triple-blue cost is the whole story: this is a discard spell priced like a control finisher, and that pricing tells you everything about how early discard was understood. Stripping every nonland card from an opponent's hand is a total reset, the kind of effect that wins a game outright if it lands at the right moment, and the design treats it as such. Six mana for a sorcery that does nothing to the board and accomplishes nothing if the hand is already empty: the payoff is purely in tempo and denial, not stability, since you spend a full turn touching neither your library nor the battlefield. The intensity of the color requirement is the brake. Blue does not get a one-sided hand-wipe cheaply, and the ensures the card only ever lived in dedicated mono-blue control shells. What makes Amnesia more than a curiosity is how thoroughly later design walked away from this model. The modern lineage of mass discard runs through black, not blue (Mind Twist, Hymn to Tourach, Liliana's various edicts), and is almost always paired with a cost the opponent pays or a tighter mana value. Amnesia is the artifact of a brief window when blue was allowed to do raw resource denial at sorcery speed, before the color pie hardened and handed that job elsewhere.