Divide by Zero

Bounce spells have always fought a losing battle against tempo math: the return-to-hand half costs you a card, the opponent recasts, and you have traded down unless that tempo converts to pressure. Learn is the wrinkle that resolves the arithmetic. The soft interaction (delaying a threat, resetting an aura or the counters on a permanent, stalling a combo turn) would ordinarily leave you a card behind, but the Lesson clause means the spell replaces itself, either by fetching a Lesson you keep in reserve or by looting through your deck. What would be pure tempo becomes a cantrip that happens to disrupt. The mana-value floor of 1 or greater is the real fence: it locks the spell out of tokens and zero-cost permanents, so it cannot answer the cheapest, most annoying things a bounce spell is otherwise tempted to hit. In exchange it is unusually flexible about what it can catch, reaching spells on the stack and permanents alike from a single line. That combination (a wide legal target set, a self-replacing instant, and a deliberate cap on the bottom end) makes it less a piece of interaction than a smoothing engine that occasionally does interaction's job, keeping a hand's card count stable while it buys time on the board.